填入适当的词。
1. I haven't heard from him_______ he went to America.
2.He won't be here_______ he is invited.
3. He will not go to the cinema______ he is very busy.
4. We found the key_______ she had left it.
5. We found the books two days ______he had gone away.
6. We had no sooner got to the station ________the train left.
7. He speaks English ______ he were an Englishman.
8.He is explaining clearly______ they can understand.
9. Do not leave the room______ you have finished the test.
10. She sang______ she went along.
