What’s electricity—It’s a form of energy _______ we use in our daily lives.

How can they learn anything useful ______ they spend all their spare time playing online games?

The biggest problem with Bob is that he never has got a/ an ___ goal in his life.

.Our team was ahead during the first half, but we _____ in the last ten minutes

He insisted that he _____ from heart trouble, but I didn’t think so.