电流变送器下限没有取0mA的原因是为了能检测断线,正常工作时不会低于(),当传输线因故障断路,环路电流降为0。
A.1mA
B.2mA
C.3mA
D.4mA
参考答案:D
All but one____take part in the conference____tomorrow.
A.is going to; that is to take place
B.are going to; that is about to take place
C.are going to; that is to be taken place
D.are going to; which is to be held
下列类别的物质中一定不含氢元素的是()。
A.酸
B.碱
C.酸式盐
D.碱性氧化物