Listen! There is a knock on the door.Who _____ it be?—It must be Jack.Just now I sent for him. [ ]

Friendship is very important and life____friends can be very boring.

“The day is coming ________ telegraph wires will be laid on to houses like water or gas.” Bell wrote to his father.

You think you’re poor, but look at people in really poor countries—it’s all ____．

Our teacher asked _________ .