Thank you _____ your telephone number. Can I call you _____ the number?
Sam spends two hours _______ his homework every day.
— Watching TV too much _______ bad for your eyes.—I’ll go to bed right away.
Do you prefer _______?
—Mr. Hu, can you tell us how to learn swimming well?—Sure. But remember we can learn nothing well _______ hard work.
I think _______ necessary for you _______ breakfast.