秦末农民战争爆发的根本原因是[ ]

A．天下大雨

B．修万里长城

C．秦的暴政

D．陈胜要当王

Had the governments and scientists not worked together , AIDS-related deaths（）since their highest in 2005.

A. had not fallen

B. would not fall

C. did not fall

D. would not have fallen