Mr. Wu___this math problem____him many times, but he still doesn’t understand it.

Peter is so kind. He often helps the old people to go _____ the busy street. [ ]

What ________happen if they have the party today?

Have you finished your homework yet?– No, not yet. I think it’ll take me __________ half an hour.

Don’t worry. Your mother is coming to help you. —_______ she doesn’t come and I am here alone?