重力式除锈机适用于钢管（）送进的防腐作业线的防腐。
A.直线
B.螺旋
C.轴向
D.横向
参考答案：A
计算：2sin60°=______．
I can't play with you. I have . homework to do.
A．much too
B．too much
C．too many
D．much more
