基本助动基本助动词只有三个:be、do、have,他们没有汇意义,只有语法作用,和实意动词一起构成谓(叫复合谓语),表达否定、疑问、时态、语态和其他语法关系。 其基本形式和作用如下表: 3.助...
否定形式:can't / couldn’t have done 例:She must have come here last night. She can't have gone there 6. may have done sth可能做过某事 否定形式:may not have done 例:Philip may have been hurt seriously in the car accident. 7.might have done sth 或许...
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