社会革命的最深刻根源在于（ ）
A．社会基本矛盾的激化
B．先进思想的传播
C．英雄人物的组织
D．人口数量的增多
参考答案：A
Had I known about this computer program, a hugeamount of time and energy ______. [ ]
A. would have been saved
B. had been saved
C. will be saved
D. was saved
涡桨发动机防喘放气活门在何时是打开的（）
A.发动机高功率状态时
B.发动机起动和小功率状态时
C.发动机任何状态下都是打开的
