—I’d like a pen which _________ well.

—Will this one _________?

—Sorry, Ann. I’m afraid that I can’t go to the magic show by David Copper Field with you.

— _____ Who knows when he will be back here again?

What is the best way you can imagine ______the overuse of water in our school? 

The experiment has_________ the possibility of the existence of any life on that planet, but it does not mean there is no life on other planets.

It gives his life a flying start ______ he has gone abroad for further education.

Drunk driving used to occur _______, but now it is under control.   

—I failed again. I wish I _________ harder.

—But you _________.

It is written clearly in the requirements that all passengers ______ check onto board 30 minutes before the plane takes off.

The children were playing games on the playground, ________ school uniforms.

—Do you think we can get there on time?

—Yes，_______ the truck doesn’t break down.