I shall never forget the days ______ I stayed in Africa, ________ has brought me a lot of advantages.

Do you have any idea ___ is actually going on in the classroom?

 —Did your father come back early last night?—Yes. It was not yet eight o’clock _______ he arrived home.

Elbert Einstein, for ______ life had once been very hard, was successful later in science .

—Our holiday in Beijing cost a lot of money.—Did it? Well, that doesn’t matter ______ you enjoyed yourselves