The old teacher used to get up before the sun ( ) so that he could catch the early bus to work.
问题描述：
The old teacher used to get up before the sun ( ) so that he could catch the early bus to work.
答案括号里填的是rose,为什么不能是rises?
答
因为主句的动词是一般过去时used,句子说过去的事情,所以用过去式rose,不能用现在时rises.
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