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?