by the time she got to class,the teacher had already started teaching
问题描述:
by the time she got to class,the teacher had already started teaching
中的by the time可以用下面那个词代换
A.when B.as soon as C.since D.while
答
when啊
可以互换的.
当她到教室的时候,老师早已开始教学.
B项 一……就……通常出现在时间状语从句中吧
而since是引导一个完整的陈述句或者时间点 自从..
while后用过去进行时当..的时候 和when有区别 但不大
when后接一般过去时