String players practice moving the fingers of the left hand up and down, while drawing the bow to and fro with the right arm — two entirely different movements.

弦乐器的演奏者练习的则是在左手的手指上下滑动的同时，用右手前后拉动琴弓——两个截然不同的动作。

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String players practice moving the fingers of the left hand up and down, while drawing the bow to and fro with the right arm-two entirely different movements.

弦乐器的演奏者练习的则是在左手的手指上下滑动的同时，用右手前后拉动琴弓——两个截然不同的动作。

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These ideas are favored because such actions required up-and-down motions of the arm, and fossil evidence indicates that the dino king was incapable of rotating or twisting its arms.

这些解释之所以比较可信是因为这些事都必须利用手臂的上下活动，而化石显示霸王龙的手臂是没办法旋转的。

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