He’d better ______a doctor if he ______well.
—As a member of bus drivers, I am proud of Wu Bin.—___________. He is a hero in my heart.
— Do you believe that paper is made _______ wood?—Yes, I do. And you can see that books are made________ paper.
— Do you know ________ this afternoon?— I'm not sure, but I'll tell you as soon as she ________.
If there is ______ pollution, the air in our city will be ________ dirtier.
By the time I locked the door, I realized I ________my keys at home.