照样子写句子。

例: fall     fly kites

     I like fall, because I can fly kites.

1. winter     play with snow

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2. summer     swim in the pool

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3. spring     climb mountains

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4. fall     play in the wind

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流体在圆形管道中作层流流动，如果只将流速增加一倍，则阻力损失为原来的（）倍。

A、2

B、4

C、8

D、16