(3)I was about to go out when the telephone rang.
(4)Hardly had I got home when the telephone rang.
(5)No sooner had I got home than the telephone rang.
(6)It won't be long before he comes back./It wasn't long before he came back.
(7)I didn't manage to understand it until he had explained it again.
(8)祈使句+and(or,or else,otherwise)+并列分句