英國(guó)學(xué)生科學(xué)讀本 Lesson 96 人體(2)

In a few years more the milk-teeth begin to go. Another set of teeth, called the permanent teeth, is growing, one under each of the milk-teeth, and pushing out the first set. Some new teeth also grow behind the milk-teeth at each side of the mouth. The new teeth are thirty-two in number, there being sixteen in each jaw. The tooth farthest back at each side of each jaw is the last to grow. You will not have these four back teeth until you are about twenty-one years of age, and so these teeth are called your "wisdom-teeth. "

幾年之后, 乳牙開(kāi)始掉落。另一套牙齒從原來(lái)的位置上長(zhǎng)出, 將乳牙擠掉并取而代之, 這就是恒齒。還有些新的牙齒也會(huì)從嘴巴兩側(cè)生長(zhǎng)出來(lái)。這一套新的牙齒共有三十二顆, 上下腭各有十六顆。每一側(cè)最遠(yuǎn)處的牙齒最后才會(huì)生長(zhǎng)出來(lái)。這四顆牙大約在你二十一歲的時(shí)候長(zhǎng)出來(lái), 因此, 稱之為“智齒”。

Permanent means "lasting, " and these second or permanent teeth ought to last you all the rest of your life. But to make them last, you must take care of them by brushing them at least twice every day with a toothbrush. Be sure to use your teeth well in chewing your food; for if you swallow your food half chewed—or "bolt" it, as people say—you will be sure to be ill and to suffer pain.

“恒”就是“持久”的意思, 而這第二批牙齒或者說(shuō)恒牙將會(huì)在你隨后的生命中一直與你相伴。然而, 想要讓它們持久, 你就必須好好照顧它們：每天至少使用牙刷刷兩次牙。請(qǐng)一定要正確使用牙齒來(lái)咀嚼食物;因?yàn)? 如果你沒(méi)有好好咀嚼便咽下食物或者像人們說(shuō)的那樣“囫圇吞下”, 那么一定會(huì)生病, 遭受痛苦。

Can you feel under your skin the lumps of firm red flesh which are called muscles? Feel the strong muscle in your upper arm, and notice how it becomes harder and shorter and thicker as your lower arm is raised, and how it relaxesas the arm is straightened again. In the whole of your body there are about four hundred such muscles.

你能否感覺(jué)到皮膚下方名為肌肉的紅色肉塊? 感受一下上臂的強(qiáng)壯肌肉, 并且仔細(xì)觀察, 當(dāng)你的小臂抬起時(shí), 這些肌肉如何變得更加堅(jiān)硬、粗短與厚實(shí);當(dāng)小臂放下時(shí), 它們又會(huì)變得松軟。整個(gè)人體共有大約四百塊這樣的肌肉。

Underneath the muscles you can feel something harder still—your bones. There are about two hundred separate bones in your body. The ends of many of these bones are joined together by strong bands. All the bones taken together form what is called the skeleton.

你還可以感覺(jué)到肌肉下方那些更為堅(jiān)硬的物質(zhì)——骨頭。人體中大約有兩百多塊獨(dú)立的骨頭, 它們?nèi)客ㄟ^(guò)韌帶連接在一起。這些骨頭就構(gòu)成了所謂的骨骼。

The ends of some of the muscles are fastened to the bones by strong cords or strings called sinews. As the muscles contract, they move the bones which are fastened to them; and this is the way in which our legs are made to move when we are walking, and our hands when we are working.

有些肌肉的末端通過(guò)名為肌腱的結(jié)實(shí)的索狀組織連接在一起。當(dāng)肌肉收縮時(shí), 它們就會(huì)牽動(dòng)與自己相連的骨頭;我們就是通過(guò)這種方法在走路時(shí)擺動(dòng)腿部, 在工作時(shí)運(yùn)用雙手。

英語(yǔ)美文