49. Not only _______ difficult to understand, but it was too long.

　 A. it was　　　 　　　　　 B. it made　　　 　　　 C. did it make　　 　 D. was it

48. _____ the people have become masters of their own country that science can really serve the people.

　　　 A. Only then 　　　　　　 　　　　　　　　　B. It is only then 　　

C. Only when　　　　　　　 　　　　　　　　　 D. It is only when

47. Not a single song ________ at yesterday’s party.

　 　 A. she sang　　　 　 B. sang she 　　　　 C. did she sing　　　 　　D. she did sing　

46. -It was careless of you to have left your clothes outside all night.

　 -My God! ______.

　 　 A. So did I　　 　　　　　　　 B. So I did 　　　　 C. So were you　　　 　　 D. So did you　

45. -David has made great progress recently.　 -_______, and _______.

　 　 A. So he has; so you have　　　　 　　　　　 B. So he has; so have you

　 　 C. So has he; so have　　　 　　　　　　　　　　　　 D. So has he; so you have　　

44. Little _____ about his own safety, though he was in great danger himself.

　 　 A. does he care　　 　 B. did he care　　　　　　 C. he cares　　　　 　　　 D. he cared　　 　　　

43. Not until all the fish died in the river _____ how serious the pollution was.

　 　 A. did the villagers realize　　 　　　　　　　　　 B. the villagers realized

　 　 C. the villagers did realized　 　　　　　　　　　　 D. didn’t the villagers realize　　　　

42. You can’t imagine ______ when they received these nice Christmas presents.

　 　 A. how they were excited　　　　　 　　　　 B. how excited they were

　 　 C. how excited were they　　 　　　　　　　　　 D. they were how excited　　　

41. -Do you know Jim quarreled with his brother?　 -I don’t know, _____.

　 　 A. nor don’t I care　 　　　　　　　　　　B. nor do I care　　　　　　

C. I don’t care neither　 　　　 　　　　　　D. I don’t care also　

40. Not until I began to work _____ how much time I had wasted.

　 　 A. didn’t I realize　 　 B. did I realize　　　　　 C. I didn’t realize　　 　　 D. I realize