四六级

　　在2017年上半年英语六级备考中，英语六级阅读的复习很关键。文都网校小编提醒大家，在做英语六级练习题之前，了解一些语法常识才会在做阅读题的过程中更好的理解文章大意，更加轻松的突破阅读难关。下面，小编给大家整理了2017年6月英语六级考试语法常识，希望能够帮到大家！

　　情态动词+have+过去分词

　　1) may(might) have + done sth, can (could) have + done sth　表示过去，推测过去时间里可能发生的事情。

　　Philip may (might) have been hurt seriously in the car accident.

　　Philip can (could) have been hurt seriously in the car accident.

　　2)　must have +done sth，对过去时间里可能发生的事情的推测，语气较强，具有"肯定"，"谅必"的意思。

　　---Linda has gone to work, but her bicycle is still here.

　　---She must have gone by bus.

　　3) ought to have done sth, should have done sth

　　本应该做某事，而事实上并没有做。否定句表示"不该做某事而做了"。

　　You ought to (should) have been more careful in this experiment.

　　He ought not to have thrown the old clothes away.(事实上已扔了。)

　　ought to 在语气上比should 要强。

　　4) needn‘t have done sth　 本没必要做某事

　　I dressed very warmly for the trip, but I　needn‘t have done so. The weather was hot.

　　5) would like to have done sth　 本打算做某事

　　I would like to have read the article, but I was very busy then.

　　英语六级备考，需要勤学多练！希望各位考生能在考前抓住有效时间进行复习，文都网校四六级频道祝各位六级复习顺利！