— ____________ is the school from the post office?

— It's about three kilometers away. [ ]

A. How many

B. How far

C. How much

下列印模材料制取印模后，室温放置时存在凝溢和渗润现象的是

A．硅橡胶印模材料
B．印模石膏
C．印模蜡
D．藻酸盐印模材料
E．聚醚橡胶印模材料