I can’t go to the cinema with you because I  _______ stay here until my mother comes back.

You'd better ____ football in the street.

—Is that boy Alan?—No, it ______ be him. He left for Beijing yesterday.

I ________ be a little bit slow, but at least I don’t make foolish mistakes. 

I ______ the poor rabbit, but I didn’t have the right drugs with me at that moment.