4.There is a new problem involved in the popularity of private cars road conditions need ---------.A.that; to be improvedB.which; to be improvedC.where; improvingD.when; improving

问题描述:

4.There is a new problem involved in the popularity of private cars road conditions need ---------.
A.that; to be improved
B.which; to be improved
C.where; improving
D.when; improving

D

A 同位语从句