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  3. An insect is not afraid of gravity, but it is in deadly fear of another force

An insect is not afraid of gravity, but it is in deadly fear of another force

游客2023-09-28  51
问题    An insect is not afraid of gravity, but it is in deadly fear of another force of nature. This force is called surface tension. A man coming out of a bath carries with him a film of water about one fiftieth of an inch in thickness. This weighs about a pound. A wet mouse has to carry its own weight in water. A wet fly has to lift many times its own weight, and as everyone knows, a fly once wetted by water or any other liquid is in a very serious position indeed. An insect going for a drink is in as great danger as a man leaning over the edge of a cliff in search of food. If it once falls into the grip of the surface tension of the water -- that is to say, gets wet -- it is likely to remain so until it drowns. A few insects contrive to be unwettable: The majority keep away from their drink by means of long proboscis.
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答案 surface tension
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