听力文摘：气球不见之后发生了什么?

Fairs, carnivals¹, festivals or anywhere you can buy helium-filled balloons, you’re sure to see at least one balloon rising into the sky after someone accidentally lets it go off.

在集市，嘉年华，节日聚会还有任何其他地方你都能买到氢气球，你至少能看到一个气球由于有人没有拿好，意外让气球飞向高空的情况。

What happens to the balloon after it rises out of sight? Well,that depends on how high the balloon goes!气球飞到看不见的地方会发生什么呢？嗯，这取决于气球飞到多高的地方！

When you inflate² a balloon, you’re actually putting gases, mostly helium,in this case , into an elastic³ container. As you add more gas, the pressure inside the balloon increases, and in response, the balloon expands…up to a point, that is! If you put in too much helium, and the pressure inside the balloon gets too much higher than the atmospheric⁴ pressure on the outside of the balloon, the balloon will burst.

当你给气球充气的时候，你充的一定是气体，大多是氢气，到一个有弹性的容器内。你加入的气体越多，气球内部的压力也随之增长，相应地，气球变大了……到了一定的大小，就是那个状态下，如果你充入更多的氢气，气球内部的压力就比气球外面的大气中的压力大，气球就会保障。

So what happens to a rising balloon? Well, if it gets caught by an air current and is carried along level to the earth’s surface, it could go a long way,even across the ocean,if the winds arrived! Of course, no balloon is perfectly⁵ sealed, no matter how tightly you tie it, so eventually the helium will leak out, and the balloon will sink.

所以一个不断向上升的气球会怎么样呢？嗯，如果它遇到气流被带到地球表面，这样可以走很远。如果有风，它甚至可以越过海洋！当然，不论怎么扎紧气球，没有气球是完全不会漏气的。因此最终氢气会泄露，气球会下沉。

1 carnivals   

狂欢节( carnival的名词复数 )； 嘉年华会； 激动人心的事物的组合； 五彩缤纷的颜色组合

参考例句：

• The Venice Carnival is one of the oldest and most famous international carnivals in the world. 威尼斯嘉年华是世界上最古老、最富盛名的国际嘉年华会之一。 来自常春藤生活英语杂志-2006年2月号
• A few exceptions would be made, he said, such as for carnivals. 他说一些免责条款将被制定出来，例如嘉年华会。

2 inflate   

vt.使膨胀，使骄傲，抬高（物价）

参考例句：

• The buyers bid against each other and often inflate the prices they pay.买主们竞相投标，往往人为地提高价钱。
• Stuart jumped into the sea and inflated the liferaft.斯图尔特跳到海里给救生艇充气。

3 elastic   

n.橡皮圈，松紧带；adj.有弹性的；灵活的

参考例句：

• Rubber is an elastic material.橡胶是一种弹性材料。
• These regulations are elastic.这些规定是有弹性的。

4 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

5 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。