若要选定目标的个数，通常选择函数（）来实现。
A、Sum
B、Avg
C、Count
D、Var
参考答案：C
炉门衬砖一般是硅砖
69. We had to _______hundreds of people because all of the seats were sold.
A．turn away
B．turn down
C．turn against
D．turn about
