By the time my parents returned home yesterday,I______the dinner already.A had cooked B cooked C have cooked D must be reported 请说明原因
问题描述：
By the time my parents returned home yesterday,I______the dinner already.
A had cooked B cooked C have cooked D must be reported 请说明原因
答
A
句子中有By the time ,用过去完成时