英文语法中,有一个概念叫:the third conditional(或the 3rd conditional),用于对过去(有别于1st conditional和2nd conditional)所发生的事情进行假设。
这种假设是不现实、或不可能发生的。因此在中文的语法书中,the 3rd conditional被归为”虚拟语气”的一类,但其实英文中还有一种叫“subjunctive”的虚拟语气(注意Subjunctive这个词的意思就是“虚拟语气”),the 3rd conditional和subjunctive有一定关联,但又不能等同,需注意区分。
The 3rd conditional的语法结构如下:
条件句:if+过去完成时;结果句:would have+过去分词。
通过英文例句,会更便于我们理解其用法:
(1)If I had held this stock 3 months longer, I would have tripled my profits.(如果我的这只股票能多持有3个月,我现在的利润可能都翻3倍了)
上面这句话隐含的意思是,事实上我之前没有能把这只股票多拿3个月,因此我也没能挣到我本应该能挣到的利润。
(2)If I had been able to solve the problem by myself, I wouldn’t have asked for your help. (如果我自己就能解决这问题,我也就不会求助于你了)
这个例句也可以这么理解:由于我过去没能解决这个问题,所以现在才来求助于你。
参考链接:
https://www.englishclub.com/grammar/verbs-conditional-third.htm
https://www.usingenglish.com/forum/threads/82158-Subjunctive-vs-conditional
The subjunctive
http://www.grammar-monster.com/glossary/subjunctive_mood.htm
http://grammar.ccc.commnet.edu/GRAMMAR/conditional2.htm