建筑物耐火等级共分几级以及二级耐火等级楼板的耐火极限分别为：

There()a dolphin show in the zoo tomorrow evening.A. wa...

单项选择题There()a dolphin show in the zoo tomorrow evening.
A. was
B. will have
C. will be

For days, smog persisted in many areas. China is()to co...

单项选择题For days, smog persisted in many areas. China is()to control air pollution.
A. take measures
B. doing business
C. taking measures

电子计算机房的主机房、基本工作间，当建筑面积超过140m2时，应设下列哪一种灭火系统：A.二氧化碳或1211B...

单项选择题电子计算机房的主机房、基本工作间，当建筑面积超过140m2时，应设下列哪一种灭火系统：