Playing on a frozen sports field sounds like a lot of fun. Isn't it rather risky, ____?

Everyone was on time for the meeting—_________ Chris,who’s usually ten minutes late for everything.

After the heavy snow, many students helped to clear away the snow ______ in our school.

There is not much time left，but________we must get there on time.

This tree looks high and strong but ____ its trunk is hollow.