水泥的代号为P·S。
A．硅酸盐
B．普通硅酸盐
C．矿渣硅酸盐
D．火山灰质硅酸盐
参考答案：C
—We can use QQ to talk with each other on the Internet.
—Really? But can you tell me _______it.
A．how I can use
B．how can I use
C．why can I use
D．when I can use
