题目内容
( ) 21. Mary was drawing on the blackboard the teacher came in.
A. when B. while C. as D. since
21. A when引导的时间状语从句多用一般过去时,且为短暂性动词。
练习册系列答案
相关题目
题目内容
( ) 21. Mary was drawing on the blackboard the teacher came in.
A. when B. while C. as D. since
21. A when引导的时间状语从句多用一般过去时,且为短暂性动词。