We should unite, for no country _____can solve the problem of the pig flu

Mary _________be late, so don’t wait for her.

I’d like to know ___________.— Maybe in the forest.

Who____ it be that is knocking at the door? — It ____ be Father, but I’m not sure. [ ]

There is no need for you to look up every new word you _____ when reading. You have to learn how to guess the meanings of new words according to the context.