而如果这两种介质的密度相差较大，就像空气和水那样，那么大部分的能量将会折射回来，只有一小部分会继续传播进入到新的介质中。
If the two media have really different densities, like air and water, then most of the energy is going to be reflected back, very little of it will keep going and get transmitted into the new medium.
不像以前那么好了。空气和水都被严重污染了。
It's not so good as before. Both the air and the water are badly polluted.
被污染的空气和水可以杀死植物、动物，甚至是人。
Polluted air and water can kill plants, animals, and even people.
水蒸发留下盐分，形成白色的地壳层，阻止空气和水进入下面的土壤。
The water evaporates and the salts are left behind, creating a white crustal layer that prevents air and water from reaching the underlying soil.
我们担心电网会崩溃、不可再生资源会枯竭、沙漠会扩张、岛屿会消失、空气和水会受到污染。
We fear the breakdown of the electric grid, the end of non-renewable resources, the expansion of deserts, the loss of islands, and the pollution of our air and water.
双方休戚相关，通过循环利用空气和水来调控彼此的温度。
By recycling air and water, the two drink together, breathe together and regulate each other's temperature.
月球上没有空气和水。因此生物在月球上不能生存。
There is no air and water on the moon. That's why no living things can live there.
技术高度发达，以至我们开始改变空气和水的成分。
The technology had got so advanced, that we had began to change the elements of air and water.
因为自身能制造空气和水，所以能不用浮出水面而环游地球。
Since it makes its own air and water, it can circumnavigate the globe without needing to surface.
清洁空气和水是人类生活的前提，也是地球上所有生命的先决条件。
Clean nair and water is a prerequisite not only for human life, but also for all life on the planet.
拥有3亿人口的美国，相比较40年前2亿人口时，空气和水都更清洁干净了。
With a population of 300 million, the United States has cleaner air and water now than 40 years ago, when the population was 200 million.
蚯蚓挖洞而把岩石颗粒带到地表，使它们经受热，冷、空气和水的作用。
Earthworms burrow and bring rock particles to the surface to be acted upon by heat, cold, air and water.
我们的城市会变得越来越拥挤，景色会变得更加杂乱，空气和水也会变得愈发肮脏。
Our cities will continue to become more crowded and noisome. The landscape will get more cluttered, the air and water even dirtier.
全球用得最多的自然资源(空气和水除外)是沙子，并且沙子正在消失。
The world's most-used natural resource (apart from water and air) is sand - and it's disappearing.
我们的发电厂可以通过采用空气和水混合冷却系统来减少蒸汽的排放量。
Our power plants could send less steam into the sky with hybrid air-and-water cooling systems.
森林被毁了还能长出来，空气和水被污染了还能被净化——但物种一旦灭绝就意味着永远失去。
Forests razed can grow back, polluted air and water can be cleaned - but extinction is forever.
近年来，许多国家都越来越意识到环境问题，每个国家都面临着，如空气和水的污染。
In recent years, many nations have become more aware of the environmental issues each nation faces, such as air and water pollution.
你并不需要请教专业咨询人士（当然你可以这样做），只需要融合这些基本元素就好：火，土，空气和水。
You don’t need to bring in a consultant (though you certainly can), just incorporate the basic elements: fire, earth, air, and water.
你并不需要请教专业咨询人士（当然你可以这样做），只需要融合这些基本元素就好：火，土，空气和水。
You don't need to bring in a consultant (though you certainly can), just incorporate the basic elements: fire, earth, air, and water.
许多人都关心和积极的，因为空气和水的污染影响每个人都大打折扣，使得城市生存和企业盈利。
Many people are concerned and active because air and water pollution affects everyone and makes it difficult for cities to survive and businesses to make a profit.
毕竟，他推断，众所周知一些单细胞生物可以进入一种类似冬眠的状态，并在没有空气和水的状态下生存数年。
After all, he reasoned, some single-celled creatures are known to enter a hibernation-like state and survive for years with no air or food.
据世卫组织总干事陈冯富珍博士说，气候变化将以极为不利的方式影响健康的一些最基本决定因素：食物、空气和水。
Continuing climate change will affect, in profoundly adverse ways, some of the most fundamental determinants of health: food, air and water, according to WHO Director-General Dr Margaret chan.
据世卫组织总干事陈冯富珍博士说，气候变化将以极为不利的方式影响健康的一些最基本决定因素：食物、空气和水。
Continuing climate change will affect, in profoundly adverse ways, some of the most fundamental determinants of health: food, air and water, according to WHO Director-General Dr Margaret chan.
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