【问】 He told me that he had handed in his exercise book____.
 A. two days ago B. after two days
 C. two days before D. in two days
 我认为选A(two days ago)和选C(two days before)都是正确的。不知您同意否?
 【答】 ago是个后置副词，放在表示时间的词语之后：two years ago([从现在算起的]两年前)。ago表示从现在算起的“……以前”，亦即使用ago的时间参照点是“现在”。请注意：在这种句型里谓语动词要用过去时：
 1. The treaty was signed three days ago at Bucharest. (Shaw)
 三天前在布加勒斯特签订了条约。
 2. John left a few minutes ago. (IME)
 约翰几分钟前离开了。
 3. A short while ago，my sister helped me to carry one of my old bookcases up the stairs.
 (New Concept English，Book 2 )
 片刻之前，我妹妹帮我把我的一个旧书橱抬上了楼。
 4. It was stolen twenty years ago，when Ted was a boy of fifteen. (同上)
 那辆自行车是在20年前当泰德还是个15岁的小伙子时被偷走的。
 two years before则是指从某一个过去时间点算起的“两年前”。因此，使用before的前题：必须有一个过去时间点作参照点(至少在心目中是如此)。注意：在这种句型里，谓语动词常常用过去完成时：
 1. Last summer，I finally left the firm that I had joined eighteen years before. (PEU)
 去年夏天，我终于离开了在那里工作了十八年的那家公司(过去的时间参照点是“去
 年夏天”，“18年前”是指去年夏天的18年前)。
 2. He said that he had seen her two days before.
 他说他两天前见过他。(过去的时间参照点：He said)
 3. I visited him two days ago，but he had gone to London five days before.
 ① 本例的分析和试译参考了徐鑫武的文章，见《外国语》1983年第五期.P.38。
 not long ago 56
 我两天前去拜访他，但他5天前就去伦敦了(“我访问他的时候”为过去时间的参照点)。
 在你所提问的试题中，he told me为过去的时间参照点，故只能选C(two days before)。请做下面的英语试题：
 1. My daughter was born____.
 A. nine years past B. for nine years
 C. nine years ago D. during nine years. (TOEFL，78. 4)
 2. Last summer，I returned to the city where I had left three months
 A. ago B. before C. since D. from now
 3. In 1984 the world population rose to over 4. 7 billion，up almost 85 million from anestimate made the year ago. (TOEFL，86. 12)