It shames to me to say it, but I told a lie when _______ at the meeting by my boss.   

The problem referred to at the meeting, if___________in time , will have a bad effect on the environment.

I have been teaching for over twenty years, but never _____ a girl as bright as Lily.

When  _______ homework , you should be careful .

It sounds like something is wrong with the car’s engine. _______, we’d better take it to the garage immediately.

Students in English-speaking countries usually address their man teacher ‘sir”, but __________ their woman teacher “madam”.

Maybe you have been to many countries, but nowhere else _____ such a beautiful palace.

Don't leave for there until__________ to do so.

---Mary looks hot and dry.
---So ___ you if you had a high fever.

________ got on the train when it started to move.