To make rivers than before, everybody is supposed to protect them. ( )
A.dirtyB.dirtierC.cleanD.cleaner
After the Olympics, people came to this city for a visit.
There are ________people in the square.
—Mike, it is the ________ time in ______ days that you’ve made the same mistake. —Sorry, sir. I’ll be more careful next time.
Please turn to page _________ and look at the __________picture in this unit.
Their school has more than two _____ teachers and _____ students.