书法艺术产生于______。
A．日本B．朝鲜C．中国D．占罗马
参考答案：C
______time went on, the people in the area came to realize how serious the environment had been polluted.
A．As
B．With
C．When
D．While
使用手砂轮时要先对什么部位进行检查？
