Question

sat语法题

Traffic was heavy, so by the time B finally arrived at the theater, we 【waited】 for her for an hour, missing the entire first act of the play.
请问：为什么括号里的要改成had been waiting？因为by the time吗？是不是只要看到by the time都用过去完成时呢？
谢谢。

Answer 1

你好！
这是一道典型的【时态搭配题】。
你说的很对！该题的关键确实与 by the time 有关。
by the time 引导时间状语从句的基本用法：
①从句用一般现在时，主句用一般将来或将来完成时。例如：
By the time he arrives,I will have finished my painting.
By the time she is six,Helen will begin to learn chinese.
② 从句用一般过去时，主句用过去完成时。例如：
By the time he was 14,Mozart had composed many pieces for the harpsichord,piano and violin sa well as for orchestras
所给句子中，by the time B finally 【arrived at 一般过去时】 the theater，因此，后面用过去完成时。但是，又由于语义表达上强调【wait】这个动作一直在进行，因此，改用过去完成进行时，即 had been waiting。
祝你开心如意！O(∩_∩)O~~

Answer 2

by the time= when

这里等待她 发生在我们到达之前，所以用过去完成时，表示过去的过去。

by the time并非一定用 过去完成时，还可以用现在完成时，一半过去式，等时态！

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