单项选择题
A.高调速汽阀 B.中调速汽阀 C.低调速汽阀 D.抽汽逆止阀
A.主汽阀 B.调速汽阀 C.各抽汽阀 D.各段逆止阀
A.114%-115% B.110%-112% C.116% D.103%-109%