作者:bot 时间:2020-12-19 08:14:57 阅读:()
助动词一般没有词意,不能单独作谓语动词。其作用在于帮助构成各种时态、语态、否定、疑问等。
1、助动词be(am, is, are, was, were, being, been)的用法
(1) be后跟现在分词构成进行时态。
Who is playing the violin?谁在拉小提琴?
She was reading a book then.那时她正在读书。
(2)be后跟过去分词构成被动语态。
He was asked to do the work.有人要他干这件工作。
You are invited to attend the meetintg.有人邀请你参加会议。
(3)be 后跟不定式作谓语,有如下几种情况:
①表示计划、安排将要发生的事。
Who are we to meet?我们要见谁呀?
I'm to have supper with John this afternoon.今天下午我要与约翰一起吃晚饭。
②表示指示、命令,否定式表禁止。
You are to see the headmaster today.今天你必须去见校长。
You are not to enter the room without permission.未经允许你不能进入房间。
③表示义务、责任等,同should。
You are to be back before 5.你得在5点钟以前回来。
What is to be done?该干什么。
④表示可能性,与情态动词may, can同义。
Such books are to be found in any library.这种书任何图书馆都有。
Not a sound was to be heard.一点声响也没有。
⑤表示后来发生的事,可以用来表示命运或注定
They say good-bye, little knowing that they were never to meet again.他们告别了,没想到再也不能相见了。
He was to regret the decision.他有一天会后悔做出这一决定的。
⑥用于习语
Where am I to go? 我该向何处去?
What am I to do? 我该怎么办?
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