但是在将近1亿年前，现代蛇类的近亲们靠着它们船桨似的尾巴在白垩纪的水流里随波起伏，拖曳着它们短小而笨拙的后腿。
But nearly 100 million years ago relatives of modern snakes undulated through Cretaceous period waters aided by a paddlelike tail and dragging a pair of short, footless hind legs.
理论预报采用STF法，在水动力计算中加入粘性与航态修正；在船模拖曳水池进行耐波性试验。
STF method with modification of viscous and bow up state was used for theory prediction, and model test for sea-keeping performance was done in towing tank.
一艘汽艇以每小时20英里的速度，拖曳着尾波滑水玩家在水上滑行。
A motorboat pulls the wakeboard rider through the water, traveling at around 20 miles an hour.
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