Smoking is bad for our health. You had better __________smoking.
Hurry up! The movie _______ for ten minutes!
--How do you like the twins?--Well, I think the elder sister is _______ but the young sister is _______.
--- There were so many books in the shopping center, I didn't know_______ .
Put on your coat, Jack! It's snowing _______ outside at the moment.
—Is that Tom in the teachers' office?--No, it ________ be him. He's gone to the hospital.