The room is in a terrible mess; it __________ have been cleaned.
The computer system suddenly_____ while he was searching for information on the Internet.
-----How far apart do Tom and Jack live? -----______I know, they live in the same neighborhood.
-----Would you please repeat it? -----Obviously, you _____me.
_____ I admit that all these problems are difficult, I don’t agree that they cannot be solved.
Having quarreled seriously three times, they have ______ and become best friends again.