We don’t know if it.If it,we won’t go out for a walk.

He is the only one of the students who _____ a winner of scholarship five times up to now.

I once lived in a house _______ roof hasfallen in.

What’s the central idea of the passage，Bob—Sorry，I can’t make________of itIt’s beyondmy ability

It was several minutes before I was of what was happening.[ ]