once做“一旦”时的用法新人教版必修一的课本原句是 Once she has made up her mind,nothing can change it.是不是一定要用完成时?

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once做“一旦”时的用法新人教版必修一的课本原句是 Once she has made up her mind,nothing can change it.是不是一定要用完成时?

once做“一旦”时的用法新人教版必修一的课本原句是 Once she has made up her mind,nothing can change it.是不是一定要用完成时?
once做“一旦”时的用法
新人教版必修一的课本原句是 Once she has made up her mind,nothing can change it.是不是一定要用完成时?

once做“一旦”时的用法新人教版必修一的课本原句是 Once she has made up her mind,nothing can change it.是不是一定要用完成时?
朋友,once表示"一旦……就……",引导时间状语从句,表示时间上的两个动作或两件事彼此紧接着发生,同时带有条件意味.若从句中的主语与主句主语相同,且谓语中含有be时,可以省略从句的主语和be.如:
①Once you have taken the examination,you will be able to relax.你一旦考完试就可以轻松一下.
②Once(it is)found,any mistake must be corrected.一旦发现任何错误就必须加以改正.
从上面的例句中可以看出,once引导条件从句是,不一定非得用现在完成时态.