人为失误一方面(),另一方面()。
参考答案:影响系统的安全性;影响系统的可靠性
一个圆锥的底面周长是12.56dm,高6dm,它的体积是______.
—You must have met him the other day.
—Oh, no, I ________.
A.hadn't
B.mustn't
C.haven't
D.didn't