need have done ,must have done ,can/could have done ,should have done 的区别是什么?意思是什么?主要用于哪种句型?请分别举例说明,

问题描述:

need have done ,must have done ,can/could have done ,should have done 的区别是什么?意思是什么?主要用于哪种句型?请分别举例说明,

need have done .本人才疏学浅,没见过这种说法,通常是need to be done,表示需要被完成.如:All the housework needs to be done today.(今天需要完成所有家务.)
must have done肯定猜测语气,表示一定已经完成了.如:He must have finished the housework.(他肯定已经完成家务了.)
could have done 表示本可能已经完成某件事,常表示结果与事实相反.can have done 不常见.如:He could have finished the housework if he didn't watch the basketball games.(如果他不看篮球赛,本应该已完成家务了.)
should have done,应该已经完成某事,这个“应该”不是指推测,而是指理论上的,或义务上的.如:According to the cookbook,the cake should have been baked well now.(根据菜谱,蛋糕应该已经被烤好了.)