—Lu does work hard. —Yeah. _____ of his time ______been spent on studies every day. 

The number of traffic accidents that _______ in developing countries _______ increasing.

— Why does the lake smell terrible?— Because large quantities of water ____.

One third of the country________covered with trees and the majority of the citizens________black people. 

No one in our class but Tom and I      that a new teacher is going to teach us English．