问题描述： By the time用法可以和when互换么?两个都能表示“当.”么? 1个回答 分类：英语 2014-10-26 问题解答： 我来补答 y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. 展开全文阅读
