---If there are ______ people driving , there will be ______ air pollution.--- Yes, the air will be fresher.

At present, the students in China take more exercise. Most of them are ______ than before. 

—Do you like the film 13 Flowers of Nanjing(金陵十三钗)？—Yes, I do．In fact, I've never seen a _______one．

______trees we plant, ______ our Mother Earth will be.

I usually do my homework _____than Mary. But she makes fewer mistakes because she is_____.