Information about the current foreign markets () very important to our company.
A. is
B. was
C. are
D. were
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直径小于()的管道,可以直接关闭煤气阀门,切断气源灭火。
A. 80mm
B. 100mm
C. 150mm
在供电设施上发生事故引起的法律责任,按供电设施产权归属确定。
A. 正确
B. 错误
The boiling and condensation points of refrigerant mainly depend on the () exerted upon it.
A. temperature
B. density
C. volume
D. pressure
不同步或不同跨两个相邻的接头在水平方向错开的距离不应小于()mm。
A. 400
B. 300
C. 500