By the time he ______ ten, he ______ about 3,000 English words.
问题描述：
By the time he ______ ten, he ______ about 3,000 English words.
A. had been, had learned B. was, had been C. was, learnedD. had been, learned
答
【答案】B. was, had been【解析】by the time1)到…时候为止 通常引导一个时间状语从句,表示“到……的时候为止”主句则表示在此时间之前某个事件已完成.值得注意的是,当从句用【过去时】时,主句通常用【过去...