The big ring of light that sometimes appears around the moon is caused when the moon shines on high clouds that are filled with tiny ice crystals．The ice crystals reflect the moon light in such a way that we see a circle of light．Rings appear around the sun，too-and for the same reason．When you see a ring around the sun or moon，usually means that a storm is coming．
月亮周围的光环是什么引起的
有时月亮周围出现大光环，这是由于月亮照在充满小粒冰晶体的高空云层上所引起的。云层里的冰晶体把月光反射，结果我们就看到了光环。太阳周围有时也出现光环，其道理也是一样。当你看到在太阳或月亮的周围出现光环时，这通常意味着暴风雨即将来临。
What Are the Rings of Saturn
Saturn is the most spectacular planet of all to see through a telescope．This is because of its shining rings．The rings probably consist of billions of chunks of ice，or icecovered rocks，that whirl around the planet’s equator in four glowing rings．It is the sunlight striking the rings that make them shine．
土星的光环是什么
通过望远镜能够看到的行星中，土星是最为壮观的。这是因为它有闪耀的光环。这些环大概是由亿万的冰块或被冰覆盖的岩石所组成，它们以四个闪光环围绕着土星的赤道旋转。是太阳光线照射在这些环上，从而使它们发光。
Why Do Stars Twinkle
The stars themselves don’t twinkle．They seem to twinkle because we see them through the air that covers the earth．As the light from a star shines down on earth，it passes．through unsteady layers of cold and warm air．The different layers of shimmering air bend the starlight in different ways so that it seems to change in brightness，and the star appears to twinkle.
星星为什么闪烁
星星本身并不会闪烁。看上去它似乎在闪烁，这是因为当我们看星星时，眼光要通过覆盖着地球的空气。当星星的光射到地球上时，它通过了不稳定的冷的和热的空气层。各种不同的空气层以不同的形式折射着星光，这样，看上去星星的亮度似乎在变化着，从而星星出现了闪烁。
How Does Water Put Out a Fire
When a fireman squirts water on a burning wall，the heat of the fire turns the mater to steam．The steam smothers the fire by shutting out the air needed by the blaze．At the same time，the water cools the burning material below its kindling temperature—the point below which it will not burn．
水是怎样灭火的
当消防队员向燃烧的墙壁喷水时，火的热量把水变成了水蒸气。蒸汽隔断了火焰燃烧所需要的空气，从而使火熄灭。同时水能使燃烧着的物质降温，降到燃烧温度即燃点以下，这样就不会再燃烧了。
Where Does Dew Come From
Dew is caused by the cooling of the air．On a clear night，after the sun has stopped warming the earth，the ground cools off quickly．When the night air touches the cooled blades of grass，the air becomes chilled，too．It gives up some of its moisture，which condenses，or changes into dewdrops．Dew doesn’t fall．It simply collects on grass and flowers or anything that is colder than the air around it．
露水是从哪里来的
露水是由于空气的变冷而产生的。在晴朗的夜晚，当太阳停止对地球的照射以后，地面就迅速地变凉。当夜晚的空气碰到冷却了的草叶时，热空气也就凉了下来。其中有些水分就凝结下来，即变成了露水。露水并不是从天空落下，它只是聚集在草、花或其他比周围的空气冷些的任何东西上。
What Is a Venus’sflytrap
The venus’sflytrap is a small carnivorous plant that lives by digesting insects．Its leaves are hinged in the middle，and hairlike triggers set the trap．Insects are attracted by the leaf’s bloodred center．When an insect touches one of the triggers，the halves spring together．Their teeth like edges form a cage that holds the victim fast，as digestive juices in the leaf digest the meal．
什么是捕蝇草
捕蝇草是靠消化昆虫而生存的一种食肉小植物。其叶子彼此铰接于中间，叶子上毛发似的触发器形成陷阱。叶子中央血红的颜色吸引着昆虫。当昆虫碰到其中一个触发器时，叶子的两边就弹起合拢。齿形的锋边形成一个囚笼，很快地捉住这个牺牲品，接着叶子中的消化液就把这顿美餐消化。
What Is Breadfruit
From its name it is easy to guess that a bread like food can be made from the starchy fruit of the tropical breadfruit tree．Its round fruit is about the size of a coconut．The mealy pulp inside looks much like bread when baked．
Islanders gather the breadfruit and roast it over hot coals．A breadfruit may also be sliced and fried like a potato or dried and pounded into flour to make breadfruit bread．
什么是面包果
从面包果这个名字就不难猜到，用热带面包果树的淀粉果实，可以制成像面包那样的食物。这种果子呈圆形，其大小和椰子果差不多，里面含淀粉的果肉烤熟后很像面包。岛上的居民把面包果采集回来并在火炭上烤熟。也可以把面包果切成薄片，然后像炸土豆那样油炸。或者把它晒干并捣碎成面粉做面包果面包。
How Do Bananas Grow
Bananas don’t grow on trees．They grow on tall stalks made up of stiff bundles of leaves．The bananas grow in bunches on a long flower stalk that bends down toward the ground．The bananas are harvested while they are still green．Bananas have no seeds．New banana plants grow from pieces of the old rootstock．
香蕉是怎样生长的
香蕉不是生长在树上，而是生长在由挺硬的叶束所组成的高大的叶柄上。香蕉成串地长在朝地弯曲的长长的花梗上。当香蕉还是青的时候就要采收。香蕉没有种子，新的香蕉幼苗是从老的根茎上生长出来的。
What Makes Waves in the Ocean
Most waves in the ocean are made by wind．It blows over the surface of the water，making ripples．As the wind pushes the ripples along，gravity tugs at them and pulls them down．They form ridges of water that travel across the sea and eventually break against a shore．A wave may travel thousands of miles from the place where it was formed．
海洋里的波浪是什么引起的
海洋里的波浪大都是由风所造成的。风刮过水面，引起波动。当风推动波浪向前时，地球引力使劲拖住它，并使之落下，从而形成水浪。这些水浪穿过海洋滚滚向前，最后冲击海岸。海浪能从它产生的地方滚动数千里。
What Causes Fog
Fog is most likely to appear when a warm，damp breeze is cooled as it passes over cold land or water and mixes with the colder air near the surface．The sudden chiling of the warmer air changes some of the moisture in the air into tiny droplets of water．These drops are not bigenough to fall as rain，but float in the air as fog．
雾是怎样形成的
当温暖而又潮湿的微风从寒冷的地面或水面吹过时，就冷却下来了，并和表面附近较冷的空气混合在一起，这时经常出现雾。暖空气突然变冷使空气中的一些水分变成了极小的水滴。这些水滴非常非常小，不能落下来成为雨，而是漂浮在空中，这就形成了雾。
How Does Frost Kill Plants
It is not the frost itself that kills the plant．The plant dies because the freezing temperature that causes frost to form also freezes the plant．As the juices inside the plant freeze，they expand and burst the delicate plant cells，killing the plant．
霜是怎样冻死植物的
冻死植物的并不是霜本身。植物之所以死掉，是由于冷冻温度所引起的。这种温度导致霜的产生，同时，也使植物受冻。当植物内部的汁液受冻时，植物就膨胀并胀破娇嫩的细胞，植物也因此死掉。