50. To play basketball and to go swimming ____ useful for character-training.

A. was　　 B. is　　 C. are　　 D. were

key: C

比较一下48-50三个题

49. Early to bed and early to rise ____ a good habit.

A. are　　 B. is　　 C. were　　 D. was

key: B

48. Both rice and wheat ____ grown in that country.

A. is　　 B. are　　 C. was　　 D. has

key: B

47. They both have some friends; but his ____ more active.

A. is　　 B. will be　　 C. was　　 D. are

key: D

46. The following ____ some other examples.

A. are　　 B. is　　 C. was　　 D. were

key: A　 the following指代的是一些其它的例子们

45. My family ____ small.

A. is　　 B. were　 C. are　　 D. makes

key: A 所指不是家里的人,而是把家作为一个单位来说.

44. Mathematics ____ the language of science.

A. are　　 B. are going to be　　 C. is　　 D. is to be

key: C Mathematics 数学

43. ____ either of your parents come to see you recently?

A. Have　　 B. Had　 C. Has　　 D. Is

key: C　

42. Half of the fruit ____ bad.

A. are B. has C. is D. have

key: C

41. When and where to build the new factory ____ yet.

A. has not decided　　　　 B. is not decided

C. are not decided　　　　 D. have not decided

key: B　 When and where to build the new factory讲的是一个事情