The number of chairs in the room __ ten. I’m afraid a number of chairs in the room ___ lost.

--- I hear a number of workers in the factory ______ out of work.--- Yes, and the number _______ quite huge.

–What ______ that? -It’s a map.

Either you or one of your students _______ to attend the meeting that is due tomorrow. 

Only 16 percent of China’s area ____ covered with forests, so ____of us should protect trees.