渣浆泵填料一般采用（）圈填料。
A、1-2
B、2-3
C、3-4
D、4-5
参考答案：C
—_____ is it from our school to Beijing Road?
—About half an hour's bus ride. Shall we go and visit it? [ ]
A. How long
B. How often
C. How far
D. How much
镶贴釉面砖，为改善砂浆和易性，可掺人不大于水泥重量（）的石灰膏。
A．5％
B．7％
C．12％
D．15％
