英语中译英

They accused that company of having been not able to protect the public.

Some overseas students need a long time to adapt to the new ediquette and custom.

It must take actions to cut dowm the loss of the typhoon.

According to the reported that many part of China suffered floods in 1998.

At the age of the old society , there is little acesses for the poor people.

英文翻译！！

TRANSFORMER

1. INTRODUCTION

The high-voltage tran**ission was need for the case electrical power is to be provided at considerable distance from a generating station. At some point this high voltage must be reduced, because ultimately is must supply a load. The transformer makes it possible for various parts of a power system to operate at different voltage levels. In this paper we discuss power transformer principles and applications.

2. TOW-WINDING TRANSFORMERS

A transformer in its simplest form consists of two stationary coils coupled by a mutual magnetic flux. The coils are said to be mutually coupled because they link a common flux.

In power applications, laminated steel core transformers (to which this paper is restricted) are used. Transformers are efficient because the rotational losses normally associated with rotating machine are absent, so relatively little power is lost when transforming power from one voltage level to another. Typical efficiencies are in the range 92 to 99%, the higher values applying to the larger power transformers.

The current flowing in the coil connected to the ac source is called the primary winding or simply the primary. It sets up the flux φ in the core, which varies periodically both in magnitude and direction. The flux links the second coil, called the secondary winding or simply secondary. The flux is changing; therefore, it induces a voltage in the secondary by electromagnetic induction in accordance with Lenz’s law. Thus the primary receives its power from the source while the secondary supplies this power to the load. This action is known as transformer action.

3. TRANSFORMER PRINCIPLES

When a sinusoidal voltage Vp is applied to the primary with the secondary open-circuited, there will be no energy transfer. The impressed voltage causes a **all current Iθ to flow in the primary winding. This no-load current has two functions: (1) it produces the magnetic flux in the core, which varies sinusoidally between zero and φm, where φm is the maximum value of the core flux; and (2) it provides a component to account for the hysteresis and eddy current losses in the core. There combined losses are normally referred to as the core losses.

The no-load current Iθ is usually few percent of the rated full-load current of the transformer (about 2 to 5%). Since at no-load the primary winding acts as a large reactance due to the iron core, the no-load current will lag the primary voltage by nearly 90º. It is readily seen that the current component Im= I0sinθ0, called the magnetizing current, is 90º in phase behind the primary voltage VP. It is this component that sets up the flux in the core; φ is therefore in phase with Im.

The second component, Ie=I0sinθ0, is in phase with the primary voltage. It is the current component that supplies the core losses. The phasor sum of these two components represents the no-load current, or

I0 = Im+ Ie

It should be noted that the no-load current is distortes and nonsinusoidal. This is the result of the nonlinear behavior of the core material.

If it is assumed that there are no other losses in the transformer, the induced voltage In the primary, Ep and that in the secondary, Es can be shown. Since the magnetic flux set up by the primary winding，there will be an induced EMF E in the secondary winding in accordance with Faraday’s law, namely, E=NΔφ/Δt. This same flux also links the primary itself, inducing in it an EMF, Ep. As discussed earlier, the induced voltage must lag the flux by 90º, therefore, they are 180º out of phase with the applied voltage. Since no current flows in the secondary winding, Es=Vs. The no-load primary current I0 is **all, a few percent of full-load current. Thus the voltage in the primary is **all and Vp is nearly equal to Ep. The primary voltage and the resulting flux are sinusoidal; thus the induced quantities Ep and Es vary as a sine function. The average value of the induced voltage given by

Eavg = turns×

which is Faraday’s law applied to a finite time interval. It follows that

Eavg = N = 4fNφm

which N is the number of turns on the winding. Form ac circuit theory, the effective or root-mean-square (rms) voltage for a sine wave is 1.11 times the average voltage; thus

E = 4.44fNφm

Since the same flux links with the primary and secondary windings, the voltage per turn in each winding is the same. Hence

Ep = 4.44fNpφm

and

Es = 4.44fNsφm

where Ep and Es are the number of turn on the primary and secondary windings, respectively. The ratio of primary to secondary induced voltage is called the transformation ratio. Denoting this ratio by a, it is seen that

a = =

Assume that the output power of a transformer equals its input power, not a bad sumption in practice considering the high efficiencies. What we really are saying is that we are dealing with an ideal transformer; that is, it has no losses. Thus

Pm = Pout

or

VpIp × primary PF = VsIs × secondary PF

where PF is the power factor. For the above-stated assumption it means that the power factor on primary and secondary sides are equal; therefore

VpIp = VsIs

from which is obtained

= ≌ ≌ a

It shows that as an approximation the terminal voltage ratio equals the turns ratio. The primary and secondary current, on the other hand, are inversely related to the turns ratio. The turns ratio gives a measure of how much the secondary voltage is raised or lowered in relation to the primary voltage. To calculate the voltage regulation, we need more information.

The ratio of the terminal voltage varies somewhat depending on the load and its power factor. In practice, the transformation ratio is obtained from the nameplate data, which list the primary and secondary voltage under full-load condition.

When the secondary voltage Vs is reduced compared to the primary voltage, the transformation is said to be a step-down transformer: conversely, if this voltage is raised, it is called a step-up transformer. In a step-down transformer the transformation ratio a is greater than unity (a1.0), while for a step-up transformer it is **aller than unity (a1.0). In the event that a=1, the transformer secondary voltage equals the primary voltage. This is a special type of transformer used in instances where electrical isolation is required between the primary and secondary circuit while maintaining the same voltage level. Therefore, this transformer is generally knows as an isolation transformer.

As is apparent, it is the magnetic flux in the core that forms the connecting link between primary and secondary circuit. In section 4 it is shown how the primary winding current adjusts itself to the secondary load current when the transformer supplies a load.

Looking into the transformer terminals from the source, an impedance is seen which by definition equals Vp / Ip. From = ≌ ≌ a , we have Vp = aVs and Ip = Is/a.In terms of Vs and Is the ratio of Vp to Ip is

= =

But Vs / Is is the load impedance ZL thus we can say that

Zm (primary) = a2ZL

This equation tells us that when an impedance is connected to the secondary side, it appears from the source as an impedance having a magnitude that is a2 times its actual value. We say that the load impedance is reflected or referred to the primary. It is this property of transformers that is used in impedance-matching applications.

4. TRANSFORMERS UNDER LOAD

The primary and secondary voltages shown have similar polarities, as indicated by the “dot-making” convention. The dots near the upper ends of the windings have the same meaning as in circuit theory; the marked terminals have the same polarity. Thus when a load is connected to the secondary, the instantaneous load current is in the direction shown. In other words, the polarity markings signify that when positive current enters both windings at the marked terminals, the MMFs of the two windings add.

Since the secondary voltage depends on the core flux φ0, it must be clear that the flux should not change appreciably if Es is to remain essentially constant under normal loading conditions. With the load connected, a current Is will flow in the secondary circuit, because the induced EMF Es will act as a voltage source. The secondary current produces an MMF NsIs that creates a flux. This flux has such a direction that at any instant in time it opposes the main flux that created it in the first place. Of course, this is Lenz’s law in action. Thus the MMF represented by NsIs tends to reduce the core flux φ0. This means that the flux linking the primary winding reduces and consequently the primary induced voltage Ep, This reduction in induced voltage causes a greater difference between the impressed voltage and the counter induced EMF, thereby allowing more current to flow in the primary. The fact that primary current Ip increases means that the two conditions stated earlier are fulfilled: (1) the power input increases to match the power output, and (2) the primary MMF increases to offset the tendency of the secondary MMF to reduce the flux.

In general, it will be found that the transformer reacts almost instantaneously to keep the resultant core flux essentially constant. Moreover, the core flux φ0 drops very slightly between n o load and full load (about 1 to 3%), a necessary condition if Ep is to fall sufficiently to allow an increase in Ip.

On the primary side, Ip’ is the current that flows in the primary to balance the demagnetizing effect of Is. Its MMF NpIp’ sets up a flux linking the primary only. Since the core flux φ0 remains constant. I0 must be the same current that energizes the transformer at no load. The primary current Ip is therefore the sum of the current Ip’ and I0.

Because the no-load current is relatively **all, it is correct to assume that the primary ampere-turns equal the secondary ampere-turns, since it is under this condition that the core flux is essentially constant. Thus we will assume that I0 is negligible, as it is only a **all component of the full-load current.

When a current flows in the secondary winding, the resulting MMF (NsIs) creates a separate flux, apart from the flux φ0 produced by I0, which links the secondary winding only. This flux does no link with the primary winding and is therefore not a mutual flux.

In addition, the load current that flows through the primary winding creates a flux that links with the primary winding only; it is called the primary leakage flux. The secondary- leakage flux gives rise to an induced voltage that is not counter balanced by an equivalent induced voltage in the primary. Similarly, the voltage induced in the primary is not counterbalanced in the secondary winding. Consequently, these two induced voltages behave like voltage drops, generally called leakage reactance voltage drops. Furthermore, each winding has some resistance, which produces a resistive voltage drop. When taken into account, these additional voltage drops would complete the equivalent circuit diagram of a practical transformer. Note that the magnetizing branch is shown in this circuit, which for our purposes will be disregarded. This follows our earlier assumption that the no-load current is assumed negligible in our calculations. This is further justified in that it is rarely necessary to predict transformer performance to such accuracies. Since the voltage drops are all directly proportional to the load current, it means that at no-load conditions there will be no voltage drops in either winding.

请帮忙翻译成中文

关键词：扩散，种子库，种子发芽，种子采食。

引言持续土壤种子库储存，虽然缺乏经验数据。测量种子命运的物种之间的种子生产与事件驱动招募具有脉冲和幼苗建立是至关重要的理解萌发下列火灾，但火灾机制缺乏物种招募限制在许多特莱斯有关萌发线索可以预期招聘审判生态系统，包括草地林地（耶茨及幼苗之间的消防活动。招募灌木霍布斯1997 ;克拉克2000年） 。种子动态encom苗在草地林地很少通过种子生产，分散在空间和时间，并观察（坎贝尔1999 ;克拉克2000 ;克拉克和损失通过捕食，腐烂和发芽戴维森2001 ;诺克斯和克拉克2006年）和种子播种（哈珀1977年） 。在火灾易发的社区后， Accu -实验表明，模拟招聘是一个持续的种子库是非常重要的种子有限的，而不是安全现场有限公司（克拉克及火灾后的招募和补偿成人铁道部-戴维森2001 ;诺克斯＆克拉克2006年） 。草地woodtality有义务在播种和resprouting土地种物种中的家庭Epacridaceae和（泰勒1995年;基思1996年） 。 Resprouting是最豆科也有天生的种子休眠，这意味着共同应对火灾温带草地木招聘幼苗可事件驱动和土地（诺克斯与克拉克2004年）和resprouters往往是散布体应在土壤中积累，如果植物生产种子每赛季少多物种死亡的丰饶在大多数年份。积累的这些种子火警（ Keeley 1977 ;木匠Recher 1979 ;贝尔**，但也取决于种子损失2001 ; Pausas等。 2004年） 。然而，通过分散resprouting不安全网站的种子去除种先天种子休眠应该积累病原体损失，种子捕食（克拉克和戴维森2001年） 。特别是，天敌可以判处自上而下对植物种群的数量限制的.

Research on Different Pyrites in Late Permian Coal of Sichuan Province，Southwestern China

ABSTRACT

A number of different pyrites in Late Permian sulfur-containing coals and some associated rocks in Sichuan province of southw estern China have been studied system-atically by optical microscope，SEM and STM for crystal shape，distribution，morphology and atomic struc- ture. The chemical composition w ere ****yzed using by EPMA，INAA techniques. The results in- dicated that there are different pyrite paragenesis and desulfurization properties in the different types of sulfur － containing coals formed on different depositional environments. Super micro- scopes reveal that there is colloidal pyrite in coal. The micro****ysis show s that the several types of pyrite have difference in element composition and physical and technological property such as susceptibility etc. The crystallization of pyrite plays an important role in concentration of major elements.

INTRODUCTION

Investigation on the sulfur in coal may date back to the begining of this century ( Thissen， 1919; White，1913) in America. In recent tw enty years，more and more articles，reports and books about sulfur have been published. Key studies of sulfur in coal include Casagrande; Ber- ner; Cohen et al in America; Hunt in Austrilia; Kizilstein in Russia and so on.

Tw o-thirds of total sulfur in the high sulfur coals in China are dominated by inorganic sul- fur，at least 95% of w hich consists of iron sulfide. Therefore，researches on pyrite，a major carri- er of sulfur w hich influnces the quality of coal，have increasingly attracted coal technologists' attention. Nantong of Sichuan province is one of the important coal production area in south- w estern China，w hich is one of the high sulfur coal regions in China. Our reseach objective is to study the character of pyrites in coal and associated rock，such as their distributions，physical and physic-chemical properties etc. ，and to supply fundamental data for coal desulfurization technology，coal processing and utilizations.

SULFUR FORMS IN SICHUAN COAL

Objective coal seams of our investigated fields are Toulianzi coal of Wuyi coal mine at Anxian county，#5 and #6 seams of Nantong coal field at Chongqing，C2 seam of Muchuan county. Basically they represent for several types of coal containing different sulfur forms in Sichuan province. Table 1 show s sulfur forms of coals at different sites.

Table 1 The Sulfur Forms in Different Coals of Sichuan Province，China

Generally，w hen total sulfur content( St. d) is less than 0. 5% ，the main sulfur form in coal is organic sulfur ( Hunt，1987) . But C2 coal seam at Muchuan countuy mainly contains inorgan- ic sulfur w hich occupys 63. 08% of total sulfur. From continental to marine environment，total sulfur content in coal increases，the sulfur forms are different. The sulfur form in coal formed on tidal flat is mainly in the form of iron sulfide( Sp. d) . The Wuyi and Nantong #6 coal seams is rich in organic sulfur( So. d) . Both of them are influenced by roof rock of lime-stone or mud-lime stone of marine facies. Moreover，there is a trend that organic sulfur content increases w ith the increases of total sulfur，and pyritic sulfur is the main form of sulfur in many Sichuan coals.

THE DISTRIBUTION OF PYRITES IN COAL

Macroscopically there are rarely single crystal or film pyrite in low sufur coal formed in al- luvial sw amp at Muchuan. How ever，there are a lot of nodular，lenticular，pisolitic，chrysan- themun-like，massive，vein-like pyrites etc. in Nantong #5，#6 coal seam w here sulfur is accu- mulated on transitional facies. At the low er part of Wuyi high sulfur coal seam，there are a lot of fine disseminated pyrites show ing lamellar structure，but no pyrite can be seen by naked eye at the middle and upper part. Nodular pyrite occasionally contains marcasite and pyritized organi** and biological relics.

Microscopically，there are single crystals and aggregates，framboid and its aggregates， globular，nodular，pore-nodular，biological，massive，vein，rod-like pyrites and marcasites in coals. Table 2 show s the quantitative statistics of 300 iron sulfide particles. Obviously，pyrites in Muchuan coal are mainly framboidal w hich are mostly associated w ith clay，and partly epigene- tic vein-like pyrite. In Nantong coal，there are a lot of nodular and cell-infilling pyrites. The py- rites in Wuyi coal are mainly euhedral crystal and framboid and their aggregates ( figure 1 － a) . Euhedral crystals are mostly octahedron. Wuyi coal contains more marchasites( figure 1 － b) . In general，framboidal morphology is present in all salinites. Similarly，framboidal pyrites in Sichuan coal are seen in all depositional facies. Using scanning electron microscope( SEM ) ，w e have observed pyritized Desulfovibrio，rod-chain bacteria，fine coccoides etc. . There are also a lot of pyritized algae such as Permocalculus Sinica，and Rhodophyceae. The crystal shapes of pyrite such as cube，octahedron，pentagonal dodecahedron and their combination can be easily observed by SEM. The cubic pyrite tends to distribute in continental facies，w hile the others are mostly devoloped in marine sediment，e. g. octahedron pyrite in Wuyi coal w as formed in ma- rine facies. The results are similar to that reported by Anchun Li et al( 1991) . Marcasite is usual- ly lamellar. Morever，crystal imprint，crack，grow lamination，defect，erosion relic and other mat- ter on crystal face have been seen by SEM. Especially colloid like structure，w hich devoloped in nodular pyrite，also has been observed. Coal pyrites，microscopically，contain a lot of pore pyrites，pyritized organi**s and marcasites.

Table 2 Micro****ysis of iron sulfide in coal

Table 2 show s that the pyrite particles in Muchuan coal are basically not liberated. In Nan- tong coal，1 ～ 5μm pyrite particles are dominant. The quantities of + 100μm pyrite particles in Nantong #6 coal are much more than those in other coals. The liberated pyrite in this size is as high as 44. 1% . In Wuyi coal，70% of pyrite particles are not liberated in 1 ～ 5μm size fraction. It results in difficulty in desulfurization. Wuyi coal also contains high organic sul- fur. therefore it is very important to study the properties of pyrites.

STM ANALYSIS ON SURFACE OF COAL PYRITES

Scanning tunneling microscope ( STM ) is an effective tool for the ****ysis of material sur- face. It directly reflects the image and structure of substance surface from 3μm to 1A scale. Eggleston( 1990，1992) and Fan ( 1991) successfully studied pyrite from other sources except in coal by using STM. In order to explain the difference in physical properties such as magnetic and oxidation ones of different pyrites，w e studied surface properties of pyrites w ith STM. The follow ings are our results and explanations:

Seven coal pyrites and tw o ore pyrites have been examined by CSTM -9000 scanning tunne- ling microscope for topography in constant-current mode and for atomic image in constant-hight mode. The scanning ranges are 2000X2000A to 3X3μm for topography. The granular，pellet， framboid-like，rod，fibre，bandary，milk colloidal and **ooth，level，uneven etc. structure had been observed on the surface of pyrite crystal or fracture by STM. On the crystal face，oxidative corrosion pit ( relics) are often observed. Generally，on fine granular surface of pyrite，fine grains are in order w hich is gradually grow n into laminalars，w hile large granular grains are at random on coarse，and uneven surfurce of pyrite，w hich may be caused by surface corro- sion. The STM images of fracture surface of pyrites in coal show that pyrite of good crystaliza- tion is granular grain ( figure 1 － c) ，w hile nodular pyrite of poor crystalization displays more **ooth and milk-colloid like face( figure 1 － d) . The above results observed by SEM indicate that there may be colloid pyrite in coal.

We have obtained some atomic images in constant-hight mode of STM ( figure 1 － e) ，they are not very nice and distinct，this is because that the pyrite is covered by an oxidational film. After the fresh surface of pyrite are covered w ith silica-oil，w e clearly observed the atomic structure of pyrite surface，and the zigzag chains in some parts. The interatomic distances reveal that the observed surface is in { 210 } direction of pyrite crystal. Eggleston and Fan observed { 100} and{ 110} direction of pyrite crystal surface.

In summary，STM is a new and effective technique for probing surface topography，struc- ture，crystal grow ing，atomic structure as w ell as surface oxidation and corrosion. STM and SEM directly prove that colloid pyrite exists indeed.

EPMA ANALYSIS OF PYRITES IN COAL

Electron probe microscope ****ysis( EPMA) is a method for composition ****ysis. The pre- cision of EPMA is 1% to 0. 1% . In this study，860-EDX EPMA of Link Coporation in U. K. and WDX-2A EPMA of Microspec Coporation in U. S. A w ere used. The latter has a bet- ter precision. Some conclusions about EPMA ****ysis of pyrite in coal are as follow ing.

Fig. 1 Microphotograph of iron sulfides in coals and associated rocks.

1. Ordinarily，besides Fe and S，pyrite in coal often contains Si，Al，Ca，Mg，Ti，Zr，Nb. The content of those elements in pyrite are proportional to those in matrix vitrinite. The Co，Ni，Cu， Pb etc，w hich can constitute the crystal latitices of pyrite，are minor in concentration，but they occur none or little in matrix vitrinite. In general，as crystal is transformed to framboid and cell- infilling pyrite，associated elements increase gradually.

2. In same coal seam，S content and S / Fe atomic ratio: euhedral crystal cell-infilling circular shape framboidal increase in the order of pyrite. This indicates that crystalization plays a role in sulfur enrichment. Either S or Fe in nodular pyrite is richer in centre than that at the edge. Apparently nucleation plays a major role in nodular pyrite formation. The framboidal pyrite in Muchuan coal has very high of S / Fe atomic ratio( 5) . It contains a large amount of Co，Ni etc. ，and Co / Fe atomic ratio is near to 3 /4. So some parts of framboids are not pyrite. Because framboid pyrite particle is **all，the determined value influenced by matrix substance is usually lower than actual value. It is only considered as referential value. But S / Fe ratio is less influ- enced.

3. High S / Fe ratio of pyrite devoloped in matrix vitrinite w as found to be 6 to 17. The S / Fe ratio of pyrite is proportional to the organic sulfur of de**ocollinite. The Fe content of the de**ocollinite in high sulfur coal is relatively low.

INAA ANALYSIS OF PYRITES IN COAL AND ASSOCIATED ROCK

Instrumental Neutron Activation Analysis( INAA ) has the advantages of high sensitivity， good accuracy，multielemental ****ysis and non-destruction. We used INAA to measure trace elements，and associated elements of pyrite for searching the genesis，physical properties of pyrite. Nine coal pyrite and tw o ore pyrite samples are ****ysed by INAA in Institute of High Energy Physics，Academia Sinica ( 11 ) . Table 3 is part of the INAA results，it reveals the follow ing facts:

1. The elements in pyrites of different coals are different paragenetic types，e. g. in the py- rite of Nantong #6 coal，∑REE，∑3 ( sum of lithogenic element) are very low ，w hile Ni，Zn， Na are higher. There are a large amount of associated elements such as Mn，Cr，∑2，V，Ba，Ca， Mg etc. in the matrix-like pyrite of Nantong.

2. In the pyrite from coal and associated rock，macroscopically，from crystal to chrysanthe- man，nodular，vein-like and matrix-like pyrite，Fe content decreases gradually，and Co，Mn， ∑REE and other assoociated elements increase as the crystalizational degree of pyrite becomes w orses. The w orse the pyrite crystal the higher the ∑3 lithogenic elements.

3. The difference betw een coal-and ore-pyrite is that ∑3 and ∑REE content is low in ore- pyrite，and As and∑1 is rich，especially for hydrothermal type of pyrite( No. 39) . 4. Table 3 show s some relations betw een INAA results and susceptibility of pyrite. Mn is closely proportional to susceptibility of pyrite. Mg，Co，Ca etc. in coal-pyrite have a relation w ith susceptibility，w hile ore-pyrites，w hich are rich in As，have low magnetic property. ∑2 ( Mn， Co，Ni，Cr) elements，∑3 elements have a relation w ith susceptibility of pyrites.

Apparently，the susceptibility of coal pyrites are all higher than that of ore pyrites. So High Gradient Magnet selection ( HGMS ) technology can remove coal pyrite better than ore py- rite. The magnet ****yses of coals indicate that susceptibilities of bituminous coal are all negative value; w hile anthracitous coals are all positive value w hich are approximate to those of coal py- rites. therefore HGMS is more suitable for the desulfurization of coking coals. We are continuing to undertake study on those fields. Here is only the brief conclusion.

CONCLUSIONS

The follow ing conclusions can be draw n from the above ****ysis:

1. The sulfur content in limnic coal is very poor w hich is the main property of framboidal pyrite. The marine-continent transitional facies coal is rich in sulfur，w hich is mainly in the form of inorganic sulfur. The nodular and cell-infilling pyrite are main types of pyrite and pyrite particles are large. The marine facies coal has high sulfur content，w hich is rich in high organic sulfur. Monocrystal，framboid pyrite and marcasite particles are **all. Nodular pyrite often contains more marcasite，pyritized organi**s and relics.

Table3 PartINAA Element Results and Susceptibility of Pyrites

Note: 1. INAA unit is ppm. Susceptibility unit is 10-7 eum /g.2.∑i = Cu +As +Se +Sb +Zn;∑2 = Co + Ni+ Cr+Mn;∑3 = Na + Al+Ca +Mg;∑ REE = La +Ce +Nd +Sm +Eu +Tb +Yb +Lu.3. - is that element hasn't been determined by INAA.

2. Liberation ****yses show that the pyrite in transitional facies coal contains more librated particles，w hile marine coal has less amount of liberated pyrite. Nantong coal contains more nodular pyrites，in w hich pyrite particles is larger and liberated. It is predicted that they possess good behavior for physical desulfurization. But Wuyi coal contains more fine crystal，framboid and pyrites are not liberated. Moreover it has very high organic sulfur，so its desulfurization behavior must be very poor.

3. By STM ，w e clearly obtain atomic image on { 210} surface of pyrite，this is another new result follow ing the studies by Eggleston and Fan for{ 100} and{ 110} of pyrite crystal sur- face respectively. Moreover，w e have observed several pyrite structures such as granular，ban- dary，milk colloid-like pyrite，as w ell as corrosoion pit and oxidational film. STM ，SEM directly prove that colloid pyrite exists in coal. STM is a very potential technique for the study of pyrite.

4. The composition ****yses show : As the pyrite crystallinity become better，Fe，S and S / Fe in coal pyrite increase，the associated elements decrease. There are Si，Al，Ca，Mg，Ti，Zr，Nb etc. in coal pyrite. The pyrite w ith high S / Fe ratio grow s in de**ocollinite w hich S / Fe atomic ratio is 6 － 17. The S / Fe ratio of pyrite is proportional to the organic sulfur in de**ocollinite.

5. The susceptibility of coal pyrites are much higher than that of ore pyrites. The suscepti- bility of coal pyrite has a relation w ith Mn，Co，Mg，Ca etc. elements. Bituminous coals have negative value of susceptibility，anthracite coals positive. HGMS is more suitable for the desulfu- rization of bituminous coals.

ACKNOWLEDGEMENTS

The authors express thanks to Institute of High Energy Physics of Academia Sinica，the University of Science and Technoloy of Beijing，Mr. Libing Liao，China University of Geosci- ence for their help w ith the use of facilities. We also w ish to acknow ledge financial support from National Natural Science Foundation of China and Genaral National Coal Cooperation of China.

REFFERENCES

D. J. Casagrande. In: Coal Bearing Strata: Recent Advances; Scott，Ed; Geological Society: London，1987，pp87 － 105

R. A. Berner. Geochimica et Co**ochimica Acta，48 ( 1984) ，605 － 615

A. D. Cohen，W. Spackman，P. Dolsen. International Journal of Coal Geology，4( 1983) ，73 － 96

J. W. Hunt. Austrilia Coal Geology，7 ( 1987) ，11 － 32.

A. M. Bailey，J. F. Sherrill，J. H. Blackson et al. In: Geochemistry of Sulfur in Fossil Fuels，ACS symposium series 429; Orr et al Ed; American Chemical Society，Washington，DC. 1990，186 － 203

Erqin Zhu，Qi Wang. In: Authigenic Mineralogy of Marine; Marine Press: Beijing，1988，32 － 49( in Chinese) Anchun Li，Lirong Chen，Shunxi Shen. Science Belletin，1991，928 － 930. ( in Chinese and in English) . C. M. Eggleston，Jr M. F. Hochella. Geochimica et Co**ochimica Acta，54 ( 1990) ，1511 － 1517 C. M. Eggleston，M. F. Hochella，Jr. American Mineralogist，77( 1992) ，221 － 224 Fu-Ren Fan，Allen J. Bard. Journal of Phsical Chemistry; 95( 1991) ，1969 － 1976 NAA Lab. . Institute of High Energy Physics，Academia Sinica，Ed. In: Applications of Neutron Activation Analysis in Environ-

mental Science，Biology and Geoscience. Atomic Energy Press : Beijing，1991，pp198 － 266( in Chinese)

( 本文由唐跃刚、任德贻合著，原载 Processing and Utilization of High-sulfur Coals Ⅴ，( Coal Science and Technology 21) ，1993 年)

英语口语考试作文

Everybody have different opinions about seatbelts, some people think it is not necessary because there's rarely usage of it, but some people think it is necessary because they think its for their own safety. I think it is necessary and essential to wear a seatbelt, it is about others and my own safety. If I don't wear a seatbelt, the posibility of accidents would happen more often. For example, if you don't wear a seltbelt when you are in the front seat and an accident accurs when your car **ashed into another car, you would be racing forward non-stop until you hit something. But if you did wear a seatbelt, you would still go forward but got stopped by the seatbelt and save your life. I strongly recommend everybody to wear their seatbelts the first thing they got in their cars, it is for your safety and others safety, that's what seatbelts are designed for, right? 够不够?我亲自写给你的.很开心帮到你.

帮忙给翻译下，急！！

We recently conducted a test in English 4, this is my first four exams in English, I feel that English 4 exam on the requirements of vocabulary is not very big, that is not to memorize words, in my It appears that more questions before the exam,

Is the best way to pass the exam, because the English level 4 exam little uncommon words, therefore, more familiar words in both questions, but also familiar with the questions of the question do to improve speed.

After talking in English 4 exam, I would say I am the views of the English language learning.

All of you should like me, have at least 12 years of English learning, learning English must have their own views. My personal view is that: first, English learning is a process of accumulation, perhaps you could have used one semester to level 4 through the English exam, but you can not master a semester's work in English. Second, in our school, most of the time are used in the English reading and writing, listening and speaking rarely taken into account, resulting in hearing and speaking of our poor, in other words, we learn so far Language can only be used for the examination.

Perhaps you, like before and I have not tried, but I want to say is do not start at any time later, now, should pay attention to the accumulation, rather than to focus on exam of the assault, should be more emphasis on listening and speaking practice, rather than just reading and writing exercises.

希望采纳