来自郭俊岭的问题
【Anumberofstudents______playingonthegroundbutIdon'tknowwhattheexactnumber______.A．are;isB．are;areC．is;isD．is;are】
Anumberofstudents______playingonthegroundbutIdon'tknowwhattheexactnumber______.
A．are;is B．are;are C．is;is D．is;are
