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第1段
1 .<-NARRATOR:-> Listen to part of a lecture in a biology class.
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第2段
1 .<-FEMALE PROFESSOR:-> So... ah... we know animals in many climates have to develop strategies..., uh ways to protect themselves
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2 .when the weather becomes especially hot and dry in the summers.
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3 .Let's start talking about how one small animal-
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4 .a snail-can do this...
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5 .Now, as you know, a snail is a very small creature,
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6 .with a soft, moist body,
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7 .most of which is protected by a hard shell.
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8 .A snail is a good example of an animal that has developed certain strategies
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9 .for coping with high temperatures
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10 .and drought, or lack of water.
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第3段
1 .First to avoid the heat,
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2 .when the sun comes out,
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3 .snails move into the shelter of vegetation...
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4 .uh...ya know... plants or leaves, to get out of the sun and into the shade.
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5 .Now of course, the ground can become very hot in the sun;
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6 .it absorbs and radiates heat,
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7 .so snails will move up off of the ground to places where it is cooler.
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8 .They may attach themselves to a wall...um... or a tree
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9 .where it is cooler than on the ground.
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第4段
1 .Now, it's not just heat that snails need to worry about.
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2 .They also need to avoid drying out due to lack of water...
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3 .so during a really warm, dry day or during the summer months,
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4 .snails secrete a sticky, slimy substance....um...
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5 .made of...ah calcium...
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6 .and it covers the opening of their shell...
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7 .um...covers and closes it up.
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8 .This keeps the moisture inside the shell...
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9 .and prevents the snails from drying out.
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10 .Snails can stay inside their shells closed up like this for a long time... even several months if it's a
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11 .really dry summer.
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12 .Their bodies...well...everything slows down
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13 .and so they don't need food...
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14 .they can survive on what food they've stored up...
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15 .but, when it rains and water is available again,
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16 .the snail opens up its shell to get some.
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