37.The biggest difference between dolphins and other land animals is that ______.

A.their brain is nearly the same size as humans'        B.they live in groups

C.they speak to each other in their own language       D.they are mammals

38.The dolphin can grow up to ______ metres long.

A.3.5  B.2.5   C.3    D.2

39.Dolphins listen to the sound through their ______.

A.ears    B.mouths   C.jaws    D.heads

40.Which of the following sentences is WRONG?

A.Dolphins can live for 20 to 30 years.

B.Dolphins often use sound to find their way.

C.Dolphins aren't friendly and they like to attack (袭击) people.

D.Dolphins can help people who are in trouble in the sea.

B

Not only adults but also teenagers have problems in their life.Here is a survey showing the main problems of teenagers.

They feel stressed because they have too much homework to do both at school and at home.They have lots of exams to ta ke.And parents usually send them to different classes at weekends.They don't have their own time to do what they are interested in.

Now more and more teenagers are getting short­sighted.They often read in bed or keep reading for a long time without having a  rest.Some of them are crazy about playing computer games.Some spend too much time watching TV.

Another serious problem among teenagers is that many of them are becoming fat.They eat too much junk food, but they take little exercise.

I think teenagers should think of ways to deal with problems.They should make a plan for study and hobbies and find time to relax as much as possible.

41.How many main problems are mentioned in the survey?

A.One.     B.Two.    C.Three.     D.Four.

42.Teenagers feel stressed because they have ______.

A.too much homework                   B.lots of exams

C.different classes to take at weekends      D.A, B and C

43.The underlined word “short­sighted” means “______” in Chinese.

A.目光短浅的    B.近视的    C.无先见的   D.小眼的

44.______ make(s) teenagers become fat.

A.Eating too much junk food       B.Taking little exercise

C.A and B                      D.Reading for a long time without having a rest

45.Teenagers can relax themselves by ______.

A.making a plan for study and hobbies    B.watching TV too much

C.reading in bed                      D.playing computer games