He was doing his homework when his father came yesterday 可不可以改成

问题描述:

He was doing his homework when his father came yesterday 可不可以改成
When his father came yesterday,he was doing his homework 那这个时间状语yesterday是从句里的咯?

改的话,要把yesterday去掉,因为WHEN放在前面就是当..的时候,说详细点吖 不懂 说得好可以采纳刚才说的不对。 另请高人解释把。