他说要是第二天下雨他们就待在家里。

　　误：He said they would stay at home if it would rain the next day.

　　正：He said they would stay at home if it rained the next day.

　　另外，当by the time后接一个句子起将状语从句时，其后的从句用一般现在时代替一般将来时，用一般过去时代替过去将来时。如下面是北京卷的一道高考题：

　　When I talked with my grandma on the phone, she sounded weak, but by the time we ______ up, her voice had been full of life.

　　A. were hanging B. had hung C. hung D. would hang

　　分析：C。从逻辑上说，当我在电话里和奶奶聊天时，她的声音听起来很虚弱；但到我们要挂电话时，她的声音又充满朝气。从逻辑上说，应该是“奶奶的声音又充满朝气”在先，“我们挂断电话”在后，如果是反过来的话，那说话者就无法听知道“奶奶的声音又充满朝气”之回事了。所以“挂断电话”应用一般过去时。另外，由于by the time后接句子引导时间状语从句时，从句谓语通常要用一般现在时代替一般将来时，用一般过去时代替过去将来时，所以选项D不能选。

　　过去将来时典型考题：

　　1. Did you predict that many students ______ up for the dance competition?

　　A. would sign B. signed C. have signed D. had signed

　　分析：A。根据主句谓语动词predict（预计）的意思可知，从句应用过去将来时，即指预计将要发生某事。又如：

　　She predicted that the improvement would continue. 她预测情况将继续好转。

　　2. He didn’t sell half as many videos as he thought he ______.

　　A. had B. would C. was D. sold

　　分析：B。he would为he would sell之省略，为过去将来时，表示在当时看来将会出现的情况。句意为：他售出的录像带还不到他设想的一半。又如：

　　It’s curious (that) Billy hasn’t phoned when he promised he would. 比利答应要打电话来的，但一直没有打，这很反常。