Most scientists seem to agree that certain limit should be set on consumption of cars to

Most scientists seem to agree that certain limit should be set on consumption of cars to ease air pollution．
A. a; the
B. /;the
C. the; /
D. the; the

(答案→)A. a; the B. /;the C. the; / D. the; the解析：考察冠词用法。第一空表示泛指，a certain limit相当于some limit意为某种限制， 第二空是特指，特指车辆的消费，句意为，大部分科学家似乎都同意应当对汽车的消费设定某种限制，为了减轻空气污染。

这下我知道了