The air inside a house or office building often has higher concentrations of contaminants .heavily p

题目

The air inside a house or office building often has higher concentrations of contaminants .heavily polluted outside air.
A.than does
B.more
C.as some that are
D.like of A
为什么选A?

答案

意思是：房屋或办公大楼内的空气 总是比室外已经严重污染的空气 有着跟高的空气污染物含量.
more/-er...than...的比较句式想必你应该知道的,does放在这里是倒装,因为前面的主语“室内空气”的动词是"has",所以than后面的主语“室外空气”动词倒装用的是does咯^^