问题补充:
By the time he was twenty, he receiveda doctor’s degree.
A B C DC received---had received
答案:
(答案→)C received---had received
解析:根据前面的时间状语,判断这里要用过去完成时。
时间:2019-12-08 19:23:42
By the time he was twenty, he receiveda doctor’s degree.
A B C DC received---had received
(答案→)C received---had received
解析:根据前面的时间状语,判断这里要用过去完成时。