The directions also advise people to limit caffeine products and to drink only half the bottle if they want a moderate amount of energy.

VOA: special.2009.07.22

Philosophers and psychologists knew for a long time that getting smacked in the head could change your mental faculties; that diseases like syphilis could make you deranged; that chemicals like caffeine and alcohol can affect how you think.

哲学家和心理学家在很久以前便知道,头部受到重创,会改变你的心理官能,像梅毒这样的疾病可以让你精神错乱,像咖啡因和酒精这样的化学药品,可以影响到你的思维

耶鲁公开课 - 心理学导论课程节选

And everyone at the office would get really tired because they don't have their caffeine.

没补充咖啡因，在办公室的每个人都会感到疲惫。

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Doctors say people should limit the amounts of alcohol and caffeine in their diets.

VOA: special.2009.03.24

And three: the amount of caffeine varies greatly.

VOA: special.2009.07.22