通过单向阀与调速阀串联,实现缸伸出时速度可调,缩回时影响。( )
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单电控电磁换向阀都具有记忆功能。( )
A. 对
B. 错
双电控电磁阀的两端电磁线圈可同时得电。()
A. 对
B. 错
The local goverment has always placed a strong emphasis ---- education and vocational training.
A. with
B. for
C. on
D. to
The meeting room is so small that it can be hold 20 people----.
A. at last
B. at first
C. at most
D. at once
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