—Tom looks very sad. What’s wrong _______ him?—An accident happened _______ his father this morning.
Neither the children nor their mother _____ scary movies when Mr White is away.
--- Lily, whose backpack is this? --- I think it _____ be Peter’s. Look! His name is on it.
The group of people _____ the hotel after walking for 6 hours. They needed to have a rest.
The little boy could _____ speak when he was 2 years old, but now he can sing wonderfully.
You will fail the exam _____ you study harder than before.