单项选择题
A.main stem stop valve
B.auxiliary steam stop valve
C.feed check or control valve
D.blow down valve
单项选择题 The（） is a smaller valve fitted in the auxiliary steam supply line, and is usually of the non-return type.
单项选择题 The（）is fitted in the main steam supply line and is usually of the non-return type.
单项选择题 The lifting pressure of （） is set in the presence of a Surveyor it is locked and cannot be changed.