助动词是协助主要动词构成谓语动词词组的词, 助动词是语法功能词,自身没有词义,不可单独使用,助动词用法有一下几种:
1)have +过去分词,构成完成时态,例如:
He has left for London. 他已去了伦敦。
By the end of last month, they had finished half of their work.
上月末为止,他们已经完成工作的一半。
2)have + been +现在分词,构成完成进行时,例如:
I have been studying English for ten years.
我一直在学英语,已达十年之久。
3)have+been +过去分词,构成完成式被动语态,例如:
English has been taught in China for many years.
中国教英语已经多年。
助动词be的用法
1) be +现在分词,构成进行时态,例如:
They are having a meeting. 他们正在开会。
English is becoming more and more important. 英语现在越来越重要。
2) be + 过去分词,构成被动语态,例如:
The window was broken by Tom.. 窗户是汤姆打碎的。
English is taught throughout the world. 世界各地都教英语。
3) be + 动词不定式,可表示下列内容:
a. 表示最近、未来的计划或安排,例如:
He is to go to New York next week.. 他下周要去纽约。
We are to teach the freshpersons. 我们要教新生。
说明: 这种用法也可以说成是一种将来时态表达法。
b. 表示命令,例如:
You are to explain this. 对此你要做出解释。
He is to come to the office this afternoon. 要他今天下午来办公室。
c. 征求意见,例如:
How am I to answer him? 我该怎样答复他?
Who is to go there? 谁该去那儿呢?
d. 表示相约、商定,例如:
We are to meet at the school gate at seven tomorrow morning. 我们明天早晨7点在校门口集合。
上一篇: 动词ing形式做定语
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