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
网友回答
A. that it is
B. to be
C. that it has been
(答案→)D. to have been
解析：句意：据说在过去的几年，艾滋病一直是那个地区的男男女女的最大的健康挑战。sth. is said to...是固定结构，所以只能选B或D再因为有时间状语over the past few years.我们必须用动词不定式的完成时。故选D。