用水房间的楼地面应比周围其他房间或走道低（）mm A.10-20 B.20-30 C_爱下问搜题

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问题单项选择题

用水房间的楼地面应比周围其他房间或走道低（）mm

A.10-20

B.20-30

C.30-40

D.40-50

答案

参考答案：B

单项选择题

当建筑物内的火灾荷载在300～400N/m2时，一、二级耐火等级建筑物的耐烧时间约为()。

（A）20min

（B）30min

（C）40min

（D）50min

选择题

―He’s never advised to achieve a balance between his job and hobbies, ________?

―Yes. His parents and teachers often offer him some advice.

A．has he

B．is he

C．hasn’t he

D．isn’t he