5.3 助动词be的用法
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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。







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