下列物质中,主要成分不是SiO2的是( )
A.水晶
B.石英
C.硅石
D.硅酸
答案:D
—Can you tell me how to use a micro blog on my phone?
—_________. But I have to finish my work first.
A.No problem
B.No way
C.Forget it
D.Don’t mention it
简述美国独立管制机构的特点。