—If there are cars there will be air pollution.—Yes. And the air will be cleaner.A. less;

问题补充：

—If there are cars, there will be air pollution.

—Yes. And the air will be cleaner.

A. less; less

B. fewer; fewer

C. less; fewer

D. fewer; less

答案：

A. less; less

B. fewer; fewer

C. less; fewer

(答案→)D. fewer; less

解析：句意：如果车辆再少些，就会有更少的大气污染。是的。而且空气会更清洁。Car为可数名词，所以用few来修饰，pollution为不可数名词，所以用little来修饰，本句为比较级的考查，都用比较级fewer和less；故选D。