用since,as,when,as soon as,while,if,after,before,until或because 填空.
1.He asked me another question ( ) I could answer the first one.
2.I was doing my homework ( ) suddenly a dog came in.
3.The students sang ( ) they went along.
4.( ) I was writing letters last night,he was watching TV.
5.I'll be more careful ( ) what you have said.
6.Please wait here ( ) I come back.
7.It is so dark outside ( ) it is raining.
8.( ) everyone is here,let's begin our meeting.
9.( ) I get to Beijing,I will write to you.
10.( ) it rains tomorrow,I will not go to Shanghai.