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【单选题】
The meaning of "lean" is the same in the sentences except for ________.A.
She leans on her husband for advice.
B.
He leaned forward to give her a kiss.
C.
They were leaning backwards, facing each other.
D.
He was leaning on the bridge, watching the boats go by.
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【简答题】密码锁控制,有一密码锁设有允许开锁键K1,密码键K2和K3,复位键K4,K1键按下后,允许开锁,K2键连续按3次和K3键连续按2次,锁才能打开,锁打开后按下复位键K4,锁又自动锁住,假设锁舌由直流线圈驱动,线圈得电锁打开。线圈失电锁锁住,试用PLC实现此功能,写出I/O地址分配并设计梯形图程序。
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