The bicycles pedal cranks keep indifferent equilibrium state when they stay in the free state, so that they can bring about disturbance between people and machines.
自行车脚蹬曲柄在自由状态时，曲柄处于随遇平衡，产生人机干扰。
The bicycles pedal cranks keep indifferent equilibrium state when they stay in the free state, so that they can bring about disturbance between people and machines.
自行车脚蹬曲柄在自由状态时，曲柄处于随遇平衡，产生人机干扰。
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