用汽水瓶扳手开启瓶盖时（如图甲所示），其受力示意图应为乙图中的哪一个？
A．
B．
C．
D．
答案：D
．— I ____ to your birthday party last Sunday.
— Unfortunately, you were out on business.
A．had come
B．came
C．would come
D．would have come
硬度最小的矿物是（）。
