液压控制阀是液压系统______元件。根据用途和工作特点不同，控制阀可分为三类: ______ 控制阀、 ______ 控制阀和______ 控制阀。
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溢流阀安装在液压系统的泵出口处，其主要作用是______ 和______ 。
流量阀是利用改变它的流通 ______来控制系统工作流量，从而控制执行元件的运动______，在使用定量泵的液压系统中，为使流量阀能起节流作用，必须与______联合使用。
调节溢流阀中弹簧压力Fn,即可调节系统压力的大小。
A. 对
B. 错
“She didn't ask me, so I didn't help her?”“You mean to say, you would have helped her ?”
A. if she asked you
B. if she were to ask you
C. had she asked you
D. were she to ask you
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