The Greens _____ China for seven years.
—Look! The boy in the white shirt ___be Tom. --It ____be him. I saw him enter the library just now.
Students should do everything they can __their study.
If you are a little careful, I think you can _____the problem.
Joan writes ____than she did 2 years ago.
—The pollution problem here seems to get more and more serious.--Yes. Something_____about it.