阅读下面短文，掌握其大意，然后从各题所给的四个选项（A、B、C和D）中，选出最佳选项。

　 One of Mark Twain’s classic novels is The Adventures of Tom Sawyer. It is 　36 in a small American town in the 19 th century. The people in this town are very traditional and 　37 a quiet life.The story is about a boy called Tom Sawyer, who lives with his aunt Polly. He is often in 38 with his aunt. Aunt Polly is very kind, 　39 Tom thinks she is always trying to control him.

　 Tom is different from 　40 children in the town. He loves adventure. He does a lot of bad things, but he never really 　41 anyone. He tries very hard not to go to school, and often jumps 　42 his bedroom window at night to meet his friends. He is very clever. One day, Aunt Polly asks him to do some painting, and he 　43 to get all the boys in the town to do the work for him by inventing a new 　44 game. It is these little stories 　45 make readers want to keep reading the novel, but it is the adventures that 　46 the most important part of the book.

　 Tom’s best friend is Huck Finn, a boy who has no home. In one adventure, they spend the night outside, and they see a man kill another man 　47 . Later in the book, Tom, Huck and another boy decide to leave the town 　48 they think that life there is too boring. They __49__ to an island in the middle of a river. They 　50 fires, catch fish and sleep under the stars. They also make a 　51 to travel up and down the river. 　52 seeing the boys for days, the people in the town think that they have died. One day, when Tom cones back to his aunt’s house to leave a letter 　53 that he is not dead, he hears his aunt talking about his funeral（葬礼）. 　54 Tom has an idea. On the morning of their funeral, the boys run back into town and 　55 their own funeral before telling everyone that they are still alive.

36. A. made　　　　　　　　　　　　 B. set　　　　　　　　　　　　　 C. taken　　　　　　　 D. written

37. A. have　　　　　　　　　　　　 B. pass　　　　　　　　　　　　 C. live　　　　　　　　　　　　 D. own

38. A. trouble　　　　　　　　　　　 B. silence　　　　　　　　　　 C. peace　　　　　　　 D. war

39. A. and　　　　　　　　　　　　　 B. but　　　　　　　　　　　　　 C. still　　　　　　　　　　　　 D. as

40. A. another　　　　　　　　　　 B. others　　　　　　　 C. the others　 D. the other

41. A. damages　　　　　　　　　 B. destroys　　　　　　　　　 C. ruins　　　　　　　　　　　 D. hurts

42. A. out of　　　　　　　　　　　 B. into　　　　　　　　　　　　 C. onto　　　　　　　　 D. in front of

43. A. tries　　　　　　　　　　　　　 B. fails　　　　　　　　 C. manages　　 D. struggles

44. A. fighting　　　　　　　　　　 B. painting　　　　　　　　　 C. touring　　　　　　　　　　 D. sailing

45. A. which　　　　　　　　　　　 B. that　　　　　　　　　　　　 C. what　　　　　　　　　　　 D. where

46. A. is　　　　　　　　　　　　　　 B. was　　　　　　　　　　　　 C. are　　　　　　　　　　　　　 D. were

47. A. in charge　　　　　　 B. in advance C. in the long term　　　　 D. in the dark

48. A. because 　　　　　　　　　 B. while　　　　　　　　　　　 C. even though　　　　　　 D. if

49. A. run into　　　　　　　 B. run away　　　　　　　　 C. run across　　　　 D. run out of

50. A. catch　　　　　　　　　　　　 B. set　　　　　　　　　　　　　 C. make　　　　　　　　　　　 D. put

51. A. bike　　　　　　　　　　　　　 B. boat　　　　　　　　　　　　 C. camel　　　　　　　　　　　 D. cage

52. A. By　　　　　　　　　　　　　　 B. Upon　　　　　　　　　　　 C. At　　　　　　　　　　　　　 D. Without

53. A. writing　　　　　　　　　　　 B. telling　　　　　　　　　　　 C. saying　　　 D. meaning

54. A. Then　　　　　　　　　　　　 B. Besides　　　　　　　　　　 C. Also　　　　　　　　　　　　 D. Lastly

55. A. join　　　　　　　　　　　　　 B. present　　　　　　　　　　 C. participate　　　　　　　 D. attend

Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes.Scientists have found the gene that determines skin color.

　 The gene comes in two versions, one of which is found in 99 per cent of Europeans.The other is found in 93 t0 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.

Scientists have changed the color of a dark - striped zebrafish(斑马鱼) to uniform gold by inserting a version of the pigment(色素) gene into a young fish.As with humans, zebrafish skin color is deter-mined by pigment cells，which contain melanin(黑色素).The number, size and darkness of melanin perpigment cell determine skin color.

It appears that, like the golden zebrafish, light - skinned Europeans also have a mutation (变异) in the gene for melanin production.This results in less pigrnented skin.

　 However, Keith Cheng, leader of the research team, points out that the mutation is different in hu-man ancl zebrafish genes.

　 Humans acquired dark skin in Africa about l.5 million years ago to protect bodies from ultra - violetrays of the sun. which can cause skin cancer.

But when modem humans leave Africa to live in northem latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin color, said Cheng.

The new discovery could lead to medical treatments for skin cancer.lt also could lead to research in-to ways to change skin color without damaging it like chemical treatment did on Michael Jackson.

56.Scientists have done an experiment on a dark -striped zebrafish in order to

A.fincl the different genes o humans'

B.prove the humans' skin color is determined by the pigment gene

C.find out the reason why the Africans' skin color is dark

D.fincl out the ways of changing people's skin color

57.lt can be inferred from the passage that　　　 .

A.nowadays people who want to change their skin color have to suffer 8 lot from the damage caused by the chemical treatment

B.Europeans and Africans have the same gene

C.the new discovery could help to find medical treatments for skin cancer

D.there are two kinds of genes

58.The passage mainly tells us that　　　 .

A.scientists have found out that people's skin color is determined by the gene

B.the new discovery could lead to research into ways to change skin color safely

C. pop king Michael Jackson often changed his skin color as he liked

D.people can not change their skin color without any pain

59.The reason why Europeans are light - skinned is probably that　　　 .

A.they are bom light - skinned people

B.light - skinned Europeans have mutation in the gene for melanin production

C. th　　　 ey have fewer activities outside

D.they pay much attention to protecting their skin

60.The writer's attitude towarcls the discovery is　　　 .

A.neutral　　　　　　　 B.negative　　　　　　　　　　 C.indifferent　　　　 D.positive