【问】 “高中英语课本第一册137页有这样一句话:It had been fifteen years since she left! 我 不理解为什么这句话的主句用过去完成时,而从句用过去时,好象换成:It was fifteenyearssince she had left!合适些。您说对吗?”(转引自《英语难题解答400则》) 【答】 《英语难题解答400则》(P.199)已经对这个问题作了回答。我们将用另一种完全不同的方法进行回答。 A.当since表示从过去的一个时间点延续至说话的现在时,通常要求主句使用动词的现在完成时,而要求since从句使用一般过去时: 1. We've been friends ever since we left school. (LASED) 自从我们毕业以来我们一直是朋友。 2. Since I was a child I have lived in England. (Shaw) 我从童年时起就一直住在英国。 3. It has been about forty years since a person could turn in paper money and get gold forit. 大约已有40年人们不再能在银行里用纸币换黄金了。 但是,当主句的谓语动词为be或seem时,则主句可以采用动词的一般现在时,当be与表示时间的词语连用时,尤其是如此: 1. It's a long time since I met you last. (Snow) 我们已经分别很久了。 2. It seems a long time since we last met. (CGEL) 自从我们上次见面以来似乎过了很长时间了。 那末,从句的动词时态是不是只能采用一般过去时呢?并不是这样。从句中的动词时态分两种情况:当since从句所指的是主句事件发生的起点时,从句通常使用一般过去时,如前面的例(1)和例(2);当since从句所指的是一直持续到现在的一段时间时,从句通常使用现在完成时: 1. I haven't seen you since I've been back. (Hemingway) 我回来以后一直没有见到你。 2. Since they have lived in London,they have been increasingly happy. (CGEL) 自从他们住到伦敦以来,他们越来越高兴。(他们现在仍在伦敦。) 3. He has never been to see me since I have been ill. (Wood) 自从我有病以来他一次也没来看我。(我现在仍在病中。) 如果主句为be+时间词语结构,则主句仍然可以用一般现在时: It's some considerable time since I have spoken to you on these matters. (Snow) 自从我和你说过这些事以来已经有不少时间了。 这样,对于我们所讨论的情况,主句与从句的时态便有四种不同的组合(例句如上): a)主句现在完成时+从句一般过去时 b)主句一般现在时+从句一般过去时 c)主句现在完成时+从句现在完成时 d)主句一般现在时+从句现在完成时 B.当主句所表示的情境属于过去时,也就是说since从句所涉及的情境不是延伸到现在,而是从过去的某个时间点延伸到另一个过去的时间点时,主句一般采用过去完成时。但是,可以用一般过去时来代替过去完成时,当主句为be+时间词语的结构时,尤其如此: 1. Two weeks had passed since Martin had seen him. (London) 马丁看见他以后已过去两周了。 2. Since the country had achieved independence,it had revised its constitution twice.(CGEL) 自从这个国家独立以来,已经两次修改了宪法。 3. It was years since I had seen her. (Snow) 我和她见过面以后有好几年了。 4. Since mother died he was very lonely. (Dreiser) 自他妈妈去世之后他一直很孤独。 在这种情况下,since从句既可以使用过去完成时,也可以使用一般过去时: 5.Since Jennie had left Martha had married .(Dreiser) 自从珍妮离开后,玛莎就结婚了。 6.Since she came to me.we had been happy.(Snow) 自从她来到我这里,我们都很高兴。 7.Since he knew her,she was a journalist. 从他认识她的时候起,她就是个新闻工作者。 不难看出,在这里,主句与从句的时态也有四种组合: a)主句过去完成时+从句过去完成时(例句1,2,5) b)主句过去时+从句过去完成时(例句3) c)主句过去完成时+从句过去时(例句6) d)主句过去时+从句过去时(例句4,7) 很容易发现,这四种组合是前四种组合的时态前移,即一般现在时前移为一般过去时,现在完成时前移为过去完成时。例如: It is years since I saw you. 自从我上次见过你已有好几年了。 It was years since I had seen you. 由此可以证明,高中英语课本中的句子It had been fifteen years since she left!是完全正确的。你将它改为It had been (或was) fifteen years since she had left!也是完全正确的。