下面是托业考试的真题的一部分，有很多人在找这些真题的，但是，大家都找不到，所以，沪江小编为大家搜集了一些真题，大家可以拿来练一练，然后好好的总结一下。

No two comets ever look identical， but they have basic features in common， one of the most obvious of which is a coma. A coma looks like a misty， patch of light with one or moretails often streaming from it in the directionaway from the Sun.Line At the heart of a comet’s coma liesa nucleus of solid material， typically no more than

(5) 10 kilometers across. The visible coma is a huge cloud of gas and dustthat has escapedfrom the nucleus， which it then surrounds like an extended atmosphere. The coma can extend as far as a million kilometersoutward from the nucleus. Around the coma thereis often an even larger invisible envelope of hydrogen gas.The most graphic proof that the grand spectacleof a comet develops from a relatively

(10) small and inconspicuous chunk of ice and dust wasthe close-up image obtained in 1986 by the EuropeanGiotto probe of the nucleus of Halley’s Comet. It turned out to be a bit like avery dark asteroid， measuring 16 by 8 kilometers. Ices have evaporated from its outer layersto leave a crust of nearly black dust allover the surface. Bright jets of gas fromevaporatingice burst out on the side facing the Sun， where the surface gets heated up， carrying dust

(15) with them. This is how the coma and the tails are created.Comets grow tails only when they get warmenough for ice and dust to boil off. As acomet’s orbit brings it closer to the Sun， first the coma grows， then two distinct tails usuallyform. One， the less common kind， contains electrically charged (i.e.， ionized) atoms of gas， which are blown off directly in the directionaway from the Sun by the magnetic field of

(20) the solar wind. The other tail is made of neutral dust particles， which get gently pushed back by the pressure of thesunlight itself. Unlike the ion tail， which is straight， the dust tailbecomes curved as the particles follow theirown orbits around the Sun.I0. The passage focuses on comets primarily in termsof their(A) orbital patterns

(B) coma and tails(C) brightness (D) size

11. The word "identical" in line I is closestin meaning to

(A) equally fast

(B) exactly alike

(C) near each other

(D) invisible

12. The word "heart" in line 4 is closest inmeaning to

 (A) center

  (B) edge

  (C) tail

  (D) beginning

13. Why does the author mention the Giotto probe in paragraph3?

  (A) It had a relatively small and inconspicuous nucleus.

  (B) It was very similar to an asteroid.

  (C) It was covered with an unusual black dust.

  (D) It provided visual evidence of the makeup of a comet’snucleus.

14. It can be inferred from the passage that the nucleusof a comet is made up of

  (A) dust and gas

  (B) ice and dust

  (C) hydrogen gas

  (D) electrically charged atoms

15. The word "graphic" in line 9 is closestin meaning to

  (A) mathematical

  (B) popular

  (C) unusual

  (D) vivid

   16. Which of the following occurred as the ices fromHalley’s Comet evaporated?

(A) Black dust was left on the comet’s surface.

(B) The nucleus of the comet expanded.

(C) The tail of the comet straightened out.

(D) Jets of gas caused the comet to increase its speed.

17. All of the following statements about the tails ofcomets are true EXCEPT：

(A) They can contain electrically charged or neutralparticles.

(B) They can be formed only when there is sufficientheat.

(C) They are formed before the coma expands.

(D) They always point in the direction away from theSun.

18. The word "distinct" in line 17 is closestin meaning to

(A) visible

(B) gaseous

(C) separate

(D) new

19. Compared to the tail of electrically charged atoms， the tail of neutral dust particles is relatively

(A) long

(B) curved

(C) unpredictable

(D) bright