九年级英语听力训练

九年级英语听力：外星人来电

Suppose one day scientists pick up a transmissionthey think isgenerated by aliens.

假如有一天，科学家收到到外星人发来的信号该怎么办呢?

Now what? Do we build a landing strip andbreak outthe welcome wagon?

我们有建造飞碟起落跑道来欢迎它们吗?

Well here's the thing about picking up alienbroadcasts.

关于接收到外来广播的事情是这样的。

The receivers scientists are currently using to listento space noise are designed to find constantsignals,or signals that are pulsing at regular intervals.

科学家接者收目前会听航天噪音，然后找出不变信号或者找出那些常规跳动的信号。

But any message carried by these signals wouldprobably be lost because the receivers can't pickup the modulation, or rapid variations, in thebase signal.

但是任何携带信息的信号都可能丢失，因为接收者在信号基地不能收集到变调或快速变化的信号。

The SETI institute, which searches for extra terrestrial life, has compared picking up asignal'smodulation to picking up the sound of a flute when it's masked by the noise of a waterfall.

对外星智能的探索研究院，专门寻找外星生物。它他们对接受到信号的变调和被瀑布声掩盖的笛声做了比较。

Luckily, scientists would still have enough data to pinpoint where in the sky the transmissioniscoming from.

幸运的是，科学家们有足够的数据来确定信号广播的位置。

And any slow changes in the broadcast frequency would reveal information aboutthe rotationand movement of the aliens' planets.

广播频率的细微变化都会揭露外星人星球的旋转和运动情况。

Okay, but how will we know if they are friendly?

九年级英语听力：地球上最成功的物种

For many scientists, a species'success is measuredby sheer numbers.

对很多科学家来说，一个物种的成功完全取决于数量。

In that case, the most successful species knowntoman is a type of bacterium known as S-A-R-11, orSAR-11 for short.

如果是那样是话，为人类所知的最成功的物种就是一种简称“SAR-11”的细菌。

Scientists estimate that there are two-hundred andforty times a billion billion billion SAR11 cells floatingaround in the oceans.

科学家们估计海洋中的SAR11细胞的数量超过2 x 10的28次方个。

Now that makes six-billion humans sound like a merehandful.

那让60亿人类听起来屈指可数。

SAR11 bacteria are known for their ability to transform one substance into another, which iswhythey are such an important part of the Earth's chemical cycles.

SAR11细菌以其转换物质的能力为人所知。而这也使得它们成为地球化学循环中重要的部分。

Although scientists are stilluncertain about SAR11's specific role, it appears to produce carbondioxide using the oxygen andcarbon from organic matter that's derived from photo synthesis.

尽管科学家不能确定SAR11的具体作用。但它似乎可以使来自于光合作用的氧气和有机物种的碳发生作用，产生二氧化碳。

Scientists speculate that SAR11plays a major role in the way the ocean's surface acts as agiant carbon pump that removescarbon dioxide from the atmosphere.

科学家推测SAR11在海洋表面扮演着重要的作用，作为一个巨大的碳泵移除空气中的二氧化碳。

The catch is that SAR11 is what is known as an uncultured organism, which means thatscientistshaven't been able to cultivate it under laboratory conditions.

但目前SAR11是为培养生物，也就是说科学家不能在实验室里培养出这种细菌。

九年级英语听力：做个乐观主义者

Research shows that whether a person is an optimistor apessimist is related to their quality of life,including their physical health.

研究表明，不管一个人是乐观还是悲观，都他的生活质量息息相关，包括身体健康。

The subjects involved first took personality tests inthe1960's and then thirty years later they completeda follow-up self-assessment of their healthstatus.

这个主题首次在二十世纪六十年代提出并做了人格测试，三十年后他们后续完成了健康状况的自我评价。

Researchers found that not only did the optimistsfrom the 1960's report better physicaland mental functioning thirty years later, but thatoptimists also lived longer on average than pessimists.

研究人员发现60年代的乐观主义者不仅身心比30年后的人更健康，而且乐观主义者比悲观主义者更长寿。

It's hardly clear that there is a causal relationship between optimism and health.

很难理清乐观与健康之间的因果关系。

it could be thatthey are related to the same underlying gene complex or set of mechanisms.

也许是因为它们与相同的潜在基因或是一套机制有关。

Still, it sure istempting to surmise that it's partly a positive attitude that keeps people alive forso long.

不过，可以肯定的是，一定程度上的积极心态能让人长寿。

It mayactually be possible that a lot of what my parents have been telling me for years is true.

实际上可能多年来我父母告诉我的许多事情都是真的。

If you think positively, good things may happen to you.

如果你积极地看待这个世界，好的事情就可能发生在你身上。