1. while/ my sister/ do/ the washing up/ she/ break/ a glass.
->
2. your teacher/ ring/ while/ you/ have/ a bath.
->
3. when/ I/ see/ her/ she/ buy/ food/ for the party.
->
4. This is the first time he went abroad.
->He hasn't
5. She started driving 1 month ago
->She has
6. We began eating when it started to rain.
-> We have
7. I last had my hair cut when I left her.
-> I haven't
8. If she had driven more carefully, she wouldn't have caused the accident.
->Had
9. Our company spent thousands of dollars upgrading our computer systems.
->It took
10. She can't sleep at night because she has a backache.
->Because of