There must have been someone who had informed the owner of the bathing center of the sudde

There have always been reputable and competent scientists who have disagreed with new theo

【C17】A．must have beenB．may have beenC．could have beenD．should have been

I have no idea who stole his wallet. It _____anyone.A. must have beenB. should have been

The Johnsons must have been out, ___there is no light which can be seen in their house ton

They must have been enjoying themselves there, or they______so long.A．can"t have stayedB．w

A．must have been providedB．might have providedC．m