Lifestyle can really throw a monkey-wrench in the process, no matter how dedicated the sleeper wants to be: no amount of iron will can compensate for a hectic work-schedule, or kids, etc.

生活方式总是会让这个过程进行得不那么顺利，不管实践者怎样努力，再多铁一般的意志也弥补不了一个繁忙的工作日程或者照顾孩子等等。

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Given the different contractions of the two different metals as a result of the cold, when it gets cold enough iron cannonballs will fall off a brass monkey.

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