英语翻译A jet plane moves down an airport runway,picking up spee

英语翻译
A jet plane moves down an airport runway,picking up speed until it lifts off the ground.A bird flaps its wings and takes off into the sky.Once in flight,both the plane and the bird soar smoothly through the air.What makes each one able to take off and remain in the air?
The answer lies partly in their body structures.The body of a bird is covered with feathers,and it is lightweight because many of the bones are hollow.The shape of its wings and tapered (锥形的) body are ideal for flight.Like birds,airplanes have tapered bodies with wings.Unlike birds,planes have engines that allow them to lift off and remain in flight.
Flight is possible for both birds and planes because they are able to deal with four forces involved in flight.These forces are lift,thrust,drag,and gravity.
Lift is produced as the wings of a bird or a plane move through air.Both kinds of wings are curved on top and flat on the bottom.Air flows more quickly over the curved top than it does over the flat bottom.This reduces the air pressure above the wing,which pulls the bird or plane upward.
Thrust is needed to make air flow over the wings to achieve lift.Thrust is the force that propels (推进) a bird or plane forward.To create thrust,a bird flaps its wings,and a plane uses one or more engines.
Drag is caused by air flowing against the body of the plane or the bird.Drag is a force that pushes against an object and slows it down.The tapered body of birds and planes gives them a streamlined (流线型的) quality and helps reduce drag so that they can gather enough speed to lift off.
Gravity is the force that both planes and birds must overcome to get off the ground.A plane is heavy and needs a lot of thrust to produce enough lift to overcome gravity and take off.In the air,the shape of the bird or plane creates balance so that gravity does not cause it to nose-dive or pitch to the side.The tails of birds and planes are important in maintaining balance.Birds and planes are able to adjust their directions by moving their wings and tails slightly.They also must make adjustments to deal with changes in wind speed and direction.

喷气式飞机在机场跑道上加速冲刺,直至飞离地面,鸟儿扑扇翅膀,直飞云霄,
飞机和鸟流畅地在空中穿梭,究竟是什么让他们能够脱离地心引力留在空中呢?
答案在他们各自的身体构造中,鸟的浑身被羽毛覆盖,而其空心的骨骼更使它轻盈,翅膀的形状,和身
体的锥形构造也十分理想.和鸟一样,飞机也有同样的带有翅膀的锥形构造,和鸟不一样的是,让飞机
起飞并在空中飞行的是引擎.
飞机和鸟能自由飞翔是因为他们能够很好的处理与飞行有关的四种力：抬升力,推力,拉力（阻力）和
重力.
抬升力是由鸟或飞机的翅膀在空气中运动时产生的,两种翅膀都是顶面具有弧线,而底面平展,气流流
经顶面时的速度要大于流经底面的速度,这样顶面的气压较弱,就产生了向上的爬升力.
推力是用来产生空气流而提供前面所说的爬升力的,它使飞机或鸟在空气中前进,鸟靠扇动翅膀得到推
力,而飞机是靠一个或多个引擎来得到.
拉力是气流对机身或鸟身的阻力,和物体的运动方向相反使其减速,流线的锥形构造让飞机或鸟降低阻
力的干扰,从而能够加速起飞.
重力是飞机或鸟起飞离地必须克服的力,飞机需要足够的推力来克服重力起飞,在空中时,飞机和鸟的
形状能够帮助他们平衡不致于跌落或者倾斜.尾部对飞机和鸟的平衡具有重要作用,他们能够通过尾巴
和翅膀的移动来调整飞行方向,同时也要应对风速风向的变化.