These achievements without the contribution of Qian Xuesen, a key leader of the New China's nuclear, missile and so on．
A. would have been unthinkable
B. would not be unthinkable
C. would be unthinkable
D. would not have been unthinkable
网友回答
(答案→)A. would have been unthinkable
B. would not be unthinkable
C. would be unthinkable
D. would not have been unthinkable
解析：（本题考查虚拟语气。题干句子中“without the contribution of Qian Xuesen”表示与过去事实相反的虚拟语气，谓语动词要用“would（not）}lave done'’。）