By the time用法可以和when互换么?两个都能表示“当.”么?

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By the time用法可以和when互换么?两个都能表示“当.”么?

By the time用法可以和when互换么?两个都能表示“当.”么?
By the time用法可以和when互换么?
两个都能表示“当.”么?

By the time用法可以和when互换么?两个都能表示“当.”么?
by本身有‘.之前’的意思.
by the time是典型的要求完成时态的词组,比如:
By then,he was 15.
那时他已经15岁了.(到那时之前.)
By the time she gets there,they will have covered everything.
她到那里之前,他们就已经掩盖了一切.

不能

不可以互换
by the time用在完成时句型里
when用在一般时态里
we will have finish the project by the time of next April.
we will finish the project when next April.

不能,用在不同的时态中