--- How many English words should I remember, Mr. Black?--- ______, the better, of course.

--- How tall the boy is! --- Yes, he is taller than __________ in his class.

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

 The weather in Beijing in summer is ___than that in Shanghai. They are different.

The Yellow River is one of _____ rivers in China.