聚会时你会……
A. 没过多久你就感觉无聊，想回去
B. 一直精力充沛，直到散场
回家后，你会……
A. 感觉疲惫，倒头就睡
B. 依然意犹未尽，兴奋不已
In hydraulic transmission system, the commonly used to control the direction of the oil is
A. throttle valves
B. speed regulaing valves
C. relief va;ves
D. directional control valves
When a two-position, five-way directional control valve is at any position, how many oil ports on the valve core?
A. 2
B. 3
C. 4
D. 5
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