You’d better take another flight to New York , for the AA 505 Flight ______ have been cancelled. But you should call the airport to make sure. 

The boy is old enough to ---------himself.

One of the National Health Regulations is that public schools ______ actively create conditions for sports facilities opened to the public.

—What will the weather be like tomorrow?—It _______ be rainy, cloudy or sunny. Who knows?

Keep up a good state of mind even if you ______ fail plenty of times.