When tired, sleep, when hungry, eat.

累了就睡，饿了就吃。

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It's never too soon to start good habits: Let baby eat when hungry, stop when full, and get enough physical activity.

让宝宝养成良好的进食习惯还是尽早为好：饿了才让宝宝吃，吃饱后就不再喂，进行足够的体育活动。

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A lion will attack people only when hungry.

狮子只有饿了才会攻击人。

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But that did not help. I was just as hungry when I came out of the water.

VOA: special.2010.08.01

There would be some sort of cooking, some attempt to store food for when people may have been hungry later, etc.

食物会被烹制,有人试着储藏食物,以防饥饿

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

When you're really tired sleep is what you want to do like when you're really hungry you want to eat.

你累了，就会想睡觉,正如你饿了想吃东西一样。

耶鲁公开课 - 心理学导论课程节选

Even when given the option to eat when hungry or to stimulate the pleasure center, the rats chose the stimulation until they were physically exhausted and on the brink of death.

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We will always enjoy a meal when hungry.

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The CBOE staff proposal comes at a time when revenue hungry states are grasping for ways to force Internet retailers like Amazon.com and Overstock.com to collect their sales taxes and, failing that, to prod their own citizens to voluntarily cough up the dough.

FORBES: California Tax Collectors Eye Buying Names Of Web Shoppers