云石机的常用锯片有（）
A.干式
B.湿式
C.干湿两用
D.合成式
参考答案：A, B, C
简述社区的构成要素。
Regulations on the levy of import duties on incoming passenger's luggage and articles shall be formulated by （）.
A. the Customs General Administration
B. the Tariff Commission
C. the State Council
D. the Economic Planning Commission
