电动差压变送器是以电为能源，它将被测压差转换成标准直流电信号。
参考答案：对
the whole process for the studies of cancer took more than a year, the technology is moving so fast that it will soon take just weeks．
A．How
B．Because
C．If
D．While
蒸压加气混凝土砌块有（）个强度等级。
A.5
B.6
C.7
D.8
