端面槽刀受轮廓影响，在刃磨时，两副后刀面磨成（）
A、平面
B、斜面
C、凸面
D、一凹一凸圆弧面
参考答案：B
In the past 5 years a great deal of money _____ improving the environment of the school.
A．is spent
B．has been spent
C．was spent
D．had been spent
迁飞
