题目：

41. Your trousers ____dirty， you must have _____washed.

    A.     is； it       B. are； it       C. are； them     D. is； them

42. Where ____rubbish， there are flies.
    A.     there are    B. there is      C. is         D. there has 

43. The Olympic Games ____held every ____years.
    A.     is； four     B. are； four     C. is； five     D. are； five

44. Many a man _____ come to help us.
    A. have    B. has     C. is     D. are

45. He is the only one of the students who _____elected.
    A. are     B. have      C. has    D. is

 46. Three-fourths of the homework _____today.
    A.     has finished         B. has been finished
    C. have finished                 D. have been finished

47. Those who ____ in ____compositions， please hand them in this afternoon
    A.     hasn‘t handed； his    B. haven’t handed； their
    C.has handed； their      D. have handed； his

48. Jane is one of the best students in her class who _____by their teacher.
    A.     are praised    B. is praised    C. praised    D. praising

49. The whole class _____the teacher attentively.
    A.     are listening to       B. is listening to
    C. are listening             D. is listening

50. The United States of America _____one of the most developed countries in the world.
    A. is      B. are     C. was     D. were

【答案解析】

 41-45 CBBBD   46-50 BBAAA