语法是考研英语的基础，这部分在硕士研究生英语考试中不再单独考查，但是语法知识贯穿在整个英语考卷的各个题型中。考研英语完型填空题会直接考查语法知识;考研英语阅读理解题和英译汉中有大量的长难句，这些句子只有具备一定的语法知识才能正确分析;考研英语作文中要写出正确无误的句子，也需要语法知识。这部分基础如果欠缺，其它的综合能力提高起来将会很慢，所以所有考生都务必重视考研语法的复习。下面新东方在线考研频道为大家分享：“2021考研英语语法基础知识点讲解：情态动词用法”。
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.
以上就是为大家分享的“ 2021考研英语语法基础知识点讲解：情态动词用法 ”文章，考研英语语法复习起来应该有所侧重，必须有针对性，否则死扣考研英语语法，不但浪费时间，也不一定能有很好的效果。提醒考生在复习语法过程中要注意以下几个方面：有一本正规的语法书、重点掌握句法、以真题为依托。希望大家能在考研英语中考出高分。