If you sleep less than 7 hours a day, you are more to catch a cold.
What ______ heavy snow. Let's go out for a walk in ______ snow, shall we?
It is pleasant to play ______ game of ______ table tennis ______ summer afternoon.
When we saw his face, we knew _____ was bad.
Biology is _____.
____ of them knew about the plan because it was secret.