A cow swallows its food twice！when a cow takes a bite of grass，she does not stop to chew it，but swallows it right away．The quickly swallowed food collects in a special part of the cow’s stomach，where the food forms into a ball called a cud．Later，when the cow is resting，she brings the wad of grass back up to the mouth for chewing．when the food is swallowed the second time，it is digested by the stomach．
牛为什么反刍
牛吃食物要分两次进行。当牛吃草时，不是停在嘴里嚼而是马上吞下去。这些很快被咽下去的食物聚集在牛胃的一个特殊部位，在那里食物形成一个被称做瘤胃的球体。随后，当牛休息时，就把一小块一小块的草团运回嘴里嚼。当食物第二次咽下时，才被牛胃所消化。
How Does a Fly Walk on the Ceiling
Each of the fly’s six feet are equipped with two tiny claws and sticky pads of hair．These enable it to cling upside down to the ceiling and stick to the smooth surface of a windowpane with equal ease．When walking upside down，the fly picks up three of its feet at a time．The other feet hold the fly firmly to the ceiling until it is their turn to step forward．
苍蝇是怎样在天花板上爬行的
苍蝇有六条腿，每条腿上都有两个小脚爪和粘性毛爪垫。这就使得苍蝇能倒立在天花板上和靠贴在光滑的玻璃窗面上又平稳又自在，当苍蝇倒立着爬行时，每次只移动三条腿。另外三条腿则把身体牢牢地固定在天花板上，一直轮到它们向前移动为止。
Why Do Earthworms Come Out After a Rain
It isn’t fully understood why earthworms sometime crawl about on the surface of the ground after a rain．But scientists think that it is probably because the rain water floods their burrows，and they must come to the surface to avoid being drowned．Earthworms cannot live long in sunlight，and once in the open they become weak and usually die．
为什么蚯蚓雨后出来
为什么蚯蚓常常雨后在地面上爬行，这一点人们还不十分了解。科学家们认为这大概是因为雨水淹没了蚯蚓的洞穴，它们必须到地面上来才能不被淹死。蚯蚓在阳光下是活不了多久的，一旦暴露在外面，它们就会变得很虚弱，而且常常会死掉。
How Do Flying Squirrels Fly
When the flying squirrel leaps from a high limb，it seems to fly through the air，but it is really gliding from branch to branch．The flying squirrel has loose folds of skin running from wrist to ankle along the sides of its body．It launches itself into the air，spreads its legs to stretch the folds of skin，and glide downward to another tree．Its long，swooping glide can cover 100or more feet．
飞松鼠是怎样飞的
当松鼠从高树枝跳出来时，看上去好像在空气中飞起来了。其实，那只不过是滑翔，从一根树枝滑到另一根树枝。松鼠在其躯体两侧，从前肢到后肢都有松软的皮褶。当它跳到空中时，伸开四肢以展开皮褶，这样就能向下滑翔到另一棵树上。松鼠这种长距离的飞扑滑翔可达100英尺，甚至更远。
Do Fish Ever Sleep
Yes，fish sleep．Because fish have no eyelids，they cannot close their eyes－and it may look as though they never do sleep．Most fish sleep by simply remaining motionless in the water in a sort of trance，in this manner，fish rest their bodies as we do when we sleep．When you see a fish lying very still in the water，it is very likely that it is “sleeping”．
鱼会睡觉吗
是的，鱼也会睡觉。因为，鱼没有眼睑，所以不能闭上眼睛。这样看上去好像它从不睡觉似的。大部分的鱼在睡觉时，只不过是在水中保持不动的宁静状态。就像人睡觉时那样，鱼就是用这种方式使它们的身体得到休息。当你看见鱼在水里一动也不动时，很可能它正在睡觉呢。
How Does a Snail Move
The broad，fleshy part of a snail’s body that rests on the ground is really its foot．Strong muscles in the foot move in a wavelike motion that slowly moves the snail forward．As the snail moves，its foot gives off slimy liquid called mucus．The mucus makes it easier for the foot to slide forward．It also enables the snail to stick to surfaces，even while hanging upside down．
蜗牛是怎样爬行的
蜗牛与地面接触的身体部位既宽大又多肉，事实上，此部位就是蜗牛的脚。足部的强健肌体似波浪般地移动着，这使蜗牛缓慢地向前移动。当蜗牛爬行时，它的脚便分泌出一种黏性液体，即黏液。这种液体使得蜗牛的脚比较容易地向前滑行。甚至当蜗牛倒悬在物体的表面时，这种黏液也能使它牢牢地粘在上面。
Do Snakes Sting with Their Tongue
No．That forked red tongue is to smell you，not sting you．A snake’s tongue is a kind of special feeler．It gives the snake an extra keen sense of smell by picking up odors from the air or ground．The flickering tongue helps the snake track down its prey and recognize other snakes of its own kind．
蛇是用舌头咬人吗
蛇的叉状形的红色舌头是用来嗅东西而不是用来咬人的。蛇的舌头是一种特殊的触觉器官。利用舌头来吸取空气中或地面上的气味，使自己具有一种非常敏锐的嗅觉。蛇利用一伸一缩的舌头来追捕猎物，并能辨认出与自己同类的其他蛇。
Are Elephants Afraid of Mice
It isn’t true that elephants are afraid of mice．The reason usually given for this belief is that a mouse will run up an elephant’s trunk．If it should try to crawl into an elephant’s trunk，the elephant would simply blow it out with a mighty sneeze．Mice are often found in the stalls of captive elephants，but the elephants pay no attention to them at all！
大象害怕老鼠吗
大象害怕老鼠并非事实。人们之所以有这种看法，原因在于认为老鼠会跑到大象的鼻子上面去。万一老鼠真的爬进了大象的鼻孔，大象就会打个强有力的喷嚏，毫不费力地把老鼠喷出去。人们常常可以在饲养大象的栏舍里发现老鼠，而大象对老鼠根本不在乎。
Why Does the Opossum Hang by Its Tail
When the opossum wraps its tail around a branch and hangs，its feet are free to gather food．The opossum spends much of its time in tree，hunting and eating．It has a special foundness for fruit．While climbing，an opossum also uses its skillful tail as an extra hand for support．
负鼠为什么把尾巴倒悬在树上
负鼠常常把尾巴绕在树枝上倒悬着，这样它可以用四只脚自由地采集食物。负鼠的大部分时间是在树上度过的，在那里不停地寻找东西吃。它对果实特别喜欢。攀树时，负鼠也运用其灵巧的尾巴作为额外的手来支撑。
Why Does a Gorilla Beat Its Chest
When a gorilla beats its chest，it is usually a warning to keep away．When the male gorilla feels threatened，he stands erect and drums his chest．Then he explodes into a charge that almost always stops short of the target．The fierce display usually drives away unwelcome visitors．One thing a gorilla does not do is beat his chest as a sign of victory after a battle．
为什么大猩猩擂击自己的胸部
每当大猩猩擂击自己的胸部时，这便是警告人们不要接近它。雄性猩猩一旦有恐惧感，它就直立起来，擂击自己的胸部。然后它发起突然进攻，这种进攻如果没有遇到什么目标，通常就会停止。大猩猩的凶猛行为常常驱走一些不速之客。有一点可以肯定，大猩猩并不以擂击自己的胸部来象征着战斗的胜利。
Can Fish Drown
Yes，fish can drown．It isn’t the water that keeps fish alive，but the oxygen in the water．Fish breathe through their gills，which draw oxygen from the water．When too many fish crowd together in a small pond or tonk，the oxygen in the water may soon be used up．When this happens，the fish suffocate，which is what happens when any animal drowns．
鱼会淹死吗
是的。鱼同样会淹死。使鱼能活着的并不是水，而是水中的氧气。鱼用其鳃进行呼吸，从水中吸取氧气。当过多的鱼拥挤在一个小水塘或小水池里时，水中的氧气很快就消耗尽。在这种情况下，鱼就会窒息而死。这与其他动物淹死的情况是完全一样的．
Do Bulls Attack When They See Red
Bulls don’t attack the bullfighter’s red cape because of its colour．The bull is colour blind．He cannot see the colour red．It is the taunting of the man that angers the bull．The bull would charge the waving cape regardless of its colour．
公牛看见红颜色就进攻吗
公牛并不是因为看见斗牛士的红颜色的帽子才向他发起进攻的。公牛天生色盲，它不可能看到颜色是红的。激怒公牛的乃是斗牛士的奚落。公牛将向挥动着的帽子进攻，不管它是什么颜色。