单项选择题
（） power is the power developed within the cylinder and can be measured by an engine indicator.
A.The shaft B.The mechanical C.The electric D.The indicated
单项选择题 The operating medium for control systems may be （）.
单项选择题 （） systems are provided with a stand-by device which will automatically be put in use in the even of the running device failing through a fault condition.
单项选择题 The difference between measured and desired values is called （）.
