高速公路、一级公路粗集料含泥量机铺检验频率（）m3/批。
A、800
B、1000
C、1500
参考答案：B
Gun control is a subject _____ American have argued for a long time.
A．of which
B．with which
C．about which
D．into which
如何鉴别硫酸铵？
