【英语时差8,16】空中舞蹈2

 A skydiver’s body is in a delicate balance. Gravity tugs¹ her downward with a constant, relentless² force, while air resistance pushes her upward. The faster she falls, the more air resistance there is, so eventually these two forces cancel out. Then she falls at a constant rate, her terminal velocity³. To link up with other skydivers in mid-air formations, skydivers need to control their terminal velocity very carefully. After all, if you’re falling at a hundred and ten miles per hour, and your friend is falling at a hundred and twenty, there’s no way you can link at all. As it turns out, your terminal velocity is determined⁴ by exactly two things–your weight, and the amount of surface area you expose to the ground. While a skydiver can’t do anything about her weight mid-fall, she can control how much area she presents downward. Stomach down, with arms and legs spread out in a kind of belly-flop, the average skydiver is likely to fall at around a hundred and ten miles per hour.

1 tugs   

n.猛拉( tug的名词复数 )；猛拖；拖船v.用力拉，使劲拉，猛扯( tug的第三人称单数 )

参考例句：

• The raucous sirens of the tugs came in from the river. 河上传来拖轮发出的沙哑的汽笛声。 来自辞典例句
• As I near the North Tower, the wind tugs at my role. 当我接近北塔的时候，风牵动着我的平衡杆。 来自辞典例句

2 relentless   

adj.残酷的，不留情的，无怜悯心的

参考例句：

• The traffic noise is relentless.交通车辆的噪音一刻也不停止。
• Their training has to be relentless.他们的训练必须是无情的。

3 velocity   

n.速度，速率

参考例句：

• Einstein's theory links energy with mass and velocity of light.爱因斯坦的理论把能量同质量和光速联系起来。
• The velocity of light is about 300000 kilometres per second.光速约为每秒300000公里。

4 determined   

adj.坚定的；有决心的

参考例句：

• I have determined on going to Tibet after graduation.我已决定毕业后去西藏。
• He determined to view the rooms behind the office.他决定查看一下办公室后面的房间。