2015年职称英语考试卫生类语法：情态动词（2）
2014-05-20 14:08 来源：医学教育网
2015年职称英语考试也开始渐渐拉开序幕，网校编辑特意整理了职称英语考试相关复习内容，希望对您有所帮助，祝您学习愉快！
3.may/might have v-ed
may/might have v-ed 表示推测过去某事“也许”发生了。may 比 might 表示的可能性在说话人看来稍大些。例如：
I can't find my keys.I may/might have left them at the school yesterday.
4.ought to/should have v-ed 和 ought not to/shouldn't have v-ed
ought to/should have v-ed 和 ought not to/shouldn't have v-ed 用于对已发生的情况表示“责备”、“不满”，分别表示“本应该…”和“本不应该…”。例如：
1）With all the work finished,I should have gone to the party last night.
2）You ought not to make fun of him.He is not the one you laugh at but learn from.
5.needn't have v-ed
needn't have v-ed 表示过去做了某事，但没有做的必要,意为“本没必要…”。例如：
You needn't have waken me up； I don't have to go to work today.
注：表示推测过去某动作发生的可能性时，就表示的可能性程度而言，must最大，could其次，may更次之，might最小。例如：
I wonder how Tom knew about your past.
He must/could/may/might have heard of it from Mary.
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