Thisschoolbag is notexpensive.Andtheprice ofit is the         of the three.

The world’s population is growing ______ and there is _______ land and water for growing rice.

— Peter is _______ than you, right? —Yes, but he is _______ runner in our class. 

There is _____pollution and ____fishes in the river now than 20 years ago.

 —The little girl’s bedroom is very clean.—Yes. It’s much ________ than her ________.