51. She …………at the door before she entered the office. A. has knocked B. knocks C. have knocked D.had knocked 52. The boy………when the explosion occurred A. is sleeping B. slept C. was sleeping D. sleeps 53. ………….everything already? Yes, he ………his part of work long ago. A. Has he done B. Did he do/has done C. Has he done/ did D. Did he do/ did 54. She ……….this exercise yesterday at 8 o’clock. A. wrote B. has written C. has writting D. was writing 55. I………………the article when I come home. A. translate B. will translate C. translated D. was translating 56. Her brother …………in Canada at the moment A. working B. works C. work D. is working 57. I……………you for ages. A. didn’t meet B. wasn’t meeting C. has met D. haven’t met 58. We will have supper when you ………..home. A. return B. returned C. have returned D. were returning 59. The library ……before I got there. A. closed B. has closed C. had closed D. have closed 60.The Olympic Games………….every four years. A. take place B. took place C. is taking place D. will take place