d me that he had two girl-friends,neither of _______ knew anything about the other.

There is someone knocking at the door. Who_______ it be—I’m not sure. It_______ be a postman.

You effort is sure to pay __________—Thank you for you encouragement.

Bob never does his homework ____ Helen. He makes a lot of mistakes.

He tried to deal with the increasing burden of his work，but he finally _____ and had to take a complete rest.