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专四考前预测——听写（1）：Sidewinder 
　　Most snakes move in a straight line， but there are some notable exceptions. One is the snake called the American sidewinder. From its name， you can probably guess that it moves side ways rather than in a straight line. And this is because it lives in the desert where the sand slips and slides. With nothing firm to push against for traction， the sidewinder has had to adapt its way of movement to the shifting sand. It pushes against the sand with the entire side of its body， and then moves sideways or sidesteps. It lays its body at about 60degree angle to the direction in which it wants to go. By doing this， the snake has more sand to push against. Then it points its head in the direction it wants to go and leaps. An added advantage gained from this method of moving may be that the snake‘s body is kept cooler by the breaking of contact with the hot sand during its leaps.