词典释义：
a long, narrow strap attached at one end to a horse's bit, typically used in pairs to guide or check a horse in riding or driving
缰绳。
a similar device used to restrain a young child
（牵小孩用）安全绳套，安全带。
〈喻〉 控制；管束，约束
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management is criticized for its unwillingness to let go of the reins of an organization and delegate routine tasks .管理层因不愿放弃机构控制权并下放日常事务的权力而受到批评。
cause (a horse) to stop or slow down by pulling on its reins
用缰绳勒（马）使停步或放慢步子，勒（马）
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he reined in his horse and waited for her .他勒住马等她。
cause (a horse) to change direction by pulling on its reins
用缰绳勒（马）使转向，勒（马）使转向
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he reined the mare's head about and rode off .他勒马掉头而去。
keep under control; restrain
控制住，约束
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with an effort, she reined back her impatience 她好不容易才按捺住了焦躁的心情。
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critics noted the failure of the government to rein in public spending .评论家们指出政府未能控制住公共开支。
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draw rein Brit . stop one's horse 〈英〉 收缰勒马 -
（
a ）free rein freedom of action or expression （行动，言论）自由he was given free rein to work out his designs . 他获得自主设计的充分自由 -
keep a tight rein on exercise strict control over; allow little freedom to 严加控制，严加约束her only chance of survival was to keep a tight rein on her feelings and words . 她仅有的活命机会在于牢牢控制住自己的感情和言谈
"Middle English： from Old French