The _ 31_ teacher, Mr. Litmus, had asked his students to study some special animal. They would write a short report, and tell the rest of the class their conclusions(结论). Some talked about dogs, others about horses, and some chose fish. But the most interesting _32_ of all was made by little Sophie.

　　　 “I found that _33_ are terribly ill- tempered（脾气坏的）,” she said, very sure of herself.

　　　 Everyone smiled, waiting for her to _34_. Then Sophie explained, “I spent hours in my house, watching flies. When they flied _35_, everything was OK, but when they found a _36_ they would really be noisy. I had always thought they made that _37_ with their wings, but they don’t. With my daddy’s telescope I watched the flies really closely, and saw that what they were really _38_ was shouting and protesting. They were so hysterical (歇斯底里的) that they couldn’t fly out of the window, and they would just _39_ their heads against the glass again and again. If only they had _40_ the butterfly that passed by, they would have seen that the top of the window was _41_. The butterfly tried to tell them, but it had no _42_ at all. The flies just kept on shouting and complaining.”

　　　 Mr. Litmus was _43_, and explained to the class that that form of fly’s behavior had nothing to do with _44_. Instead, it was an example of animals having different _45_ of intelligence .

　　　 And this was what _46_ a big disorder in the science class. Many parents had to come and complain because their children had _47_ their parents among the least intelligent of creatures! This, said the children, was because the parents did nothing but complain, and they _48_ listened to anyone.

　　　 Mr. Litmus had to do a lot of explaining, and quite a few parents _49_. It helped some of them realized that, although they weren’t _50_, they often behaved not terribly intelligently.

31.　 A. geography　　　　　　 B.　 head　　　　　　　 　 C.　 physics　　　　 　 D.　 science

32.　 A.　 discovery B.　 invention C.　 activity D.　 direction

33.　 A.　 insects B.　 flies C.　 butterflies D.　 bats

34.　 A.　 cheer B.　 begin C.　 discuss D.　 continue

35.　 A.　 quickly B.　 repeatedly C.　 normally D.　 directly

36.　 A.　 door　　　　　　　　　　 B.　 window　　　　　　　　 C.　 light　　　　　　　　　　 D.　 wall

37.　 A.　 force　　　　　　　　　　 B.　 wind　　　　　　　　　　 C.　 result　　　　　　　　　 D.　 noise

38.　 A.　 finding B.　 hating C.　 doing D.　 imagining

39.　 A.　 shook B.　 leaned C.　 beat D.　 turned

40.　 A.　 watched　　　　　　　 B.　 obeyed　　　　　　　　 C.　 caught　　　　　　　　　 D. heard

41.　 A.　 shut B.　 windy C.　 open D.　 clean

42.　 A.　 effect B.　 wonder　　　　　　　　 C.　 doubt D.　 reason

43.　 A.　 worried B.　 amused　　　　　　　　 C.　 encouraged D.　 learned

44.　 A.　 pleasure B.　 excitement　　　　　　 C.　 joy D.　 anger

45.　 A.　 levels　　　　　　　　　 B.　 areas　　　　　　　　　　 C.　 senses　　　　　　　　　 D.　 fields

46.　 A.　 removed B.　 caused　　　　　　　　 C.　 reduced D.　 solved

47.　 A.　 respected B.　 listed C.　 separate D.　 admitted

48.　 A.　 never B.　 always C.　 almost D.　 already

49.　 A.　 turned up B.　 gone back C.　 calmed down　　　　 D.　 held on

50.　 A.　 poor B.　 busy C.　 serious　　　　　　　　 D.　 stupid

Science seems to be getting closer to answering a very old mystery. Homing pigeons can be 　36　 hundreds of miles from their homes. When they are let to go to 　37　 again, they find their way home. Because of this special ability to 　38　,pigeons have been used 　 39　 messengers for hundreds of years.

Today people even breed homing pigeons for 　40　 at a sport. The birds are shipped to some chosen 　41　 a few hundred miles away. Then all of them are let to go together. The winner is the bird that gets home 　42　.A good race can make it home from 500 miles away 　43　 a single day.

　 The mystery of the homing pigeons is how they 　 44　 directions and how they find home. The first part seems to be pretty well 　 45　,and we know of two ways that pigeons tell directions. First, they use the sun. Experiments show that homing pigeons can tell 　46　 by the sun. What happens when the 　47　 is darkly overcoat by clouds and no one can 　48　 where the sun is? Then the pigeons still find their way home.

　Naturally, people have wondered whether pigeons might have a built-in compass　 49　 that would tell them about the direction of the 　　 50 　 magnetic(磁的)field. Many different kinds of experiments were 　 51　 　.Here’s what the scientists decided 　 52　 they had made experiments many times. When pigeons can see the sun, they use it as their 　 　53　 　 means of direction-finding. When they can’t see the sun, they use some 　54　 way to sense direction from the earth’s magnetic field.

　 But how do pigeons know 　55　 direction is toward home? What do they use that we would call a map? These are other questions to be answered.

36. A. carried B. taken　　　　 　　　　　　 C. shipped　　　　 　　　　 D. brought

37. A. escape B. get　　　　　 　　　 C. fly　　　　　　　　　　　　　　　　 D. run

38. A. find home B. sense directions　 C. send messages　　　 D. make friends

39. A.by B. as　　　　　　　　　　 C. for　　　　　 　　　　　　　　　　 D. to

40.A.performing B. directing　　　　　 C. showing　　　 　　　　 D. racing

41.A.place B. port　　　　　　　　 C. city　　　　　　　　　　　　 D. country

42.A.fast B. quickly　　　　　　 C. safely　　　　 　　　　　　　　　 D. first

43.A.on B. at　　　　　　　　　　 C. in　　　　　　 　　　　　　　 D. over

44.A.tell B. recognize　　　　　　　　 C. realize　　　 　　　　　　 D. know

45.A.explained B. answered　　 　　 C. shown　　　　　　　　　　 D. understood

46.A.courses B. roads　　　　　　　 C. directions　　 　　　　　 D. ways

47.A.sun B. heaven　　　　　　　　　　 C. land　　　　　　　　　　　　　　　 D. sky

48.A.see B. find　　　　　　　　　 C. notice　　　　　　　　　　　　　　 D. observe

49.A.anything B. something　 　　 C. someone　　　　　　　　 D. anyone

50.A.earth’s B. sun’s　　　　　　　　 C. planet’s　　　　　　　　　　　　　 D. destination’s

51.A.carried B. done　　　　　　　　 C. taken　　　　　　　　　　　　　　 D. had

52.A.before B. when　　　　　　　　　　　 C. while　　　　　　　　　　　　　　 D. after

53.A.important B. major　　　　　　　 C. main　　　　　　　　　　　　　　　 D. most

54.A.quick B. strange　　　　　　 C. special　　　　　　　　　　　　　 D.easy

55.A.what B. where　　　　　　　　　　 C. how　　　　　　　　　　　　　　　 D. which

Only after he was on the half way did he (意识到)________ that he was in the opposite

　 direction.