1、 The brain sustains the elementary activities of animal survival such as respiration, adequate rest and a beating heart.
大脑维持着动物生存的基本活动，如呼吸、充足的休息和心跳。
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2、 Understanding this cycle is important, not only because it sustains life on Earth, but also because it is bound up with the rate of global warming.
理解这种循环很重要，不仅因为碳循环维持地球上的生命，而且因为它对于全球变暖的速度有密切关系。
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