Question

AIDS is said______the biggest health challenge to both men and women in that area over the past few years.

A.that it is                           B.to be

C.that it has been                  D.to have been

Answer 1

D

解析:

根据时间状语“over the past few years”可判断出要用“动词+ing”形式的完成式，表示动作发生在谓语动词之前。