1.过去进行时如何分辨did与was/weredoing?
2.单选:I_______whenhearrived.
AwasshoppingBshoppedCshoppingDshops
3.单选I____whilehewasplayingthepiano.
AwasshoppingBshoppedCshoppingDshops
4.填空what______you____whenhearrived?
5.填空what_______you_______whilehewasshopping?