No one________ be more generous；he has a heart of gold.         

--The man in a black suit _______ be our youth worker. -- I’m sure it _____ be him. I saw him in the laboratory building some minutes ago.            

 —I think the man over there must be Bob.—It ______ be him. He has gone to Paris.

Delta, the American airline, is sometimes jokingly explained “Don’t expect your luggage to arrive” because it ______ be very slow.

Some aspects of a pilot's job      be boring, and pilots often      work at inconvenient hours．