When you are learning English, use it, ________ you won’t make great progress.
—Look! That man looks like Mr Green.—It can’t be him. He _________ to America.
This is _______ empty bottle. But it is _______useful one.
When you are sleeping, you had better______ all the windows closed.
— Could you tell me ______?— Yes. It’s next to the supermarket.
— Did you see Dr Ma yesterday afternoon?— No. When I got to his office, he ______ already.