1.过去进行时如何分辨did与was/were doing?
问题描述：
1.过去进行时如何分辨did与was/were doing?
2.单选：I _______ when he arrived.
A was shopping B shopped C shopping D shops
3.单选I ____ while he was playing the piano.
A was shopping B shopped C shopping D shops
4.填空what ______ you ____ when he arrived?
5.填空what_______you_______while he was shopping?
答
1、过去式用did,过去进行时用was/were doing
2、A
3、A
4、were doing
5、were doing
这里需要注意when\while的区别.