They became friends again that day. Until then, they _____ to each other for nearly two years.

By the time she ________ home, her parents will have prepared some delicious food for her. 

The professor walked onto the platform and seated himself in a chair, ____ for answering questions. 

The fact that so many people still smoke in public place _______that we may need  antionwide campaign  to raise awareness of the riks of smoking.

By the time he realizes the mistake he ________，it will be too late for him to do anything about it.