1、As my father _was leaving (leave) the house,the postman__arrived___(arrive).2、Tom__was working___(work)in the garden while I__was sitting___(sit) in the sun.3、As I__was walking___(walk)down the street,I__met___(meet)Charlie.4、While he_was reading___(read)the letter,he__heard___(hear)a knock at the door.5、While mother__was preparing___(prepare)lunch,Janet__was setting__(set)the table.6、She_dropped____(drop)the tray when I__was speaking___(speak)to her.绝对正确