阅读理解

阅读下列短文，从每题所给的四个选项中选出最佳选项。

　　Every animals is a living radiator (散热器)--heat formed in its cells and given off through its skin. Warm blooded animals keep a normal temperature by continuously replacing lost surface heat: smaller animals, which have more skin for every ounce of body weight, must produce heat faster than bigger ones. Because smaller animals burn fuels faster, scientists say they live faster. The speed at which an animal lives is determined by measuring the rate at which it uses oxygen. A chicken, for example, uses one-half cubic centimeters of oxygen every hour for each gram it weighs. The tiny shrew-mouse used four cubic centimeters of oxygen every hour for each gram it weighs. Because it uses oxygen eight times as fast, it is said that the shrew-mouse is living eight times as fast as the chicken. The smallest of the warm-blooded animals, the humming-bird, lives a hundred times as fast as an elephant. There is a limit to how small a warm-blooded animal can be. A mammal or bird that weighs only two and a half grams would starve to death. It would burn up its food too rapidly and would not he able to eat fast enough to supply itself more fuel.

1．The passage says that every animal is a living radiator because it _____.

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A．produces heat in its body cells

B．burns fuel to produce heat

C．sends out heat through its skin

D．takes in oxygen for burning fuel

2．Small animals are said to live faster than big ones because they _____.

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A．have more skin for their weight

B．replace lost heat faster

C．burn fuel faster than big ones

D．keep a higher body temperature

3．The amount of oxygen an animal uses depends on _____.

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A．the heat the body produces

B．the food it eats

C．its size and shape

D．the length of time it lives

4．According to the passage, which of the following inferences is possibly right?

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A．There is no limit as to how large a warm-blooded animal can be.

B．The humming-bird lives faster than any other warm-blooded animals.

C．Small animals have less skin for their body weight than large ones.

D．The humming-bird is the smallest of the warm-blooded animals.