—The bedroom is too dirty.______ we clean it?—Of course.

He is a very careful man, but he ________ make mistakes which seem ridiculous

Without the ‘ greenhouse effect’, the earth ____ be about thirty-three degrees Celsius cooler than it is.

John went to the hospital alone.If he ________ me about it, I would have gone with him.

_______it not been for the free ticket, I would not have gone to the cinema.