18 A2+ bones

CHAPTER 1 Bones WHAT DO YOU KNOW ABOUT BONES? When you see bones in a museum, they look hard, dry, and dead. But when they are inside our bodies, they are living things. They grow and change, and they can even repair themselves when they are broken. Bones are amazing things! When a human baby is born, it has about 270 soft bones. When the baby starts to grow, those bones get bigger and harder, and some of them join together. Adults have only 206 bones. By the age of about 25, a person's bones stop growing. Now the person is as tall as he'll ever be!

第一章骨头你对骨头了解多少？ 当你在博物馆里看到骨头时，它们看起来又硬又干，像死了一样。 但当它们进入我们的身体时，它们就是有生命的东西。 他们成长和改变，甚至当他们被打破时，他们可以自我修复。 骨头是很神奇的东西！人类婴儿出生时，大约有270块软骨头。 当婴儿开始成长时，这些骨头会变得更大更硬，有些骨头会连在一起。 成年人只有206块骨头。 到25岁左右，人的骨骼就会停止生长。 现在这个人已经长得很高了！

One of the most important parts of the skeleton is the skull. The 22 skull bones are like a case for the brain. The smallest bone in the body is found here. It is called the stapes, and it is part of the ear. It is only 2.5—3.3 millimeters long. The only skull bone people can move is the jaw. It is used to open, close, and move the mouth. A person's spine goes down the middle of the back. It is very important because people need it to stand up straight. It also helps people move and bend. The spine isn't one bone, but 26 small bones that look like rings. The ribs are connected to the spine. Most people have 24 ribs, 12 on the left and 12 on the right. Some people, however, are born with one or two ribs more or less. The ribs are like a case for the heart. So if someone falls, the ribs might get hurt, but the heart will be safe.

头骨是骨骼中最重要的部分之一。 这22块头骨就像是大脑的盒子。 人体内最小的骨头在这里。 它被称为镫骨，是耳朵的一部分。 它只有2.5-3.3毫米长。 人类唯一可以移动的头盖骨是下巴。 它用来打开、关闭和移动嘴巴。 人的脊椎从背部中间向下延伸。 它非常重要，因为人们需要它来站直。 它还能帮助人们移动和弯曲。 脊椎不是一块骨头，而是26块看起来像环的小骨头。 肋骨与脊柱相连。 大多数人有24根肋骨，左边12根，右边12根。 然而，有些人天生就有或多或少的一根或两根肋骨。 肋骨就像心脏的外壳。 所以如果有人摔倒，肋骨可能会受伤，但心脏是安全的。

At the top of the leg is the femur. This is the longest, biggest, and strongest bone in the body. When people stand, walk, or run, all their weight falls on this bone. More than 50 percent of a person's bones are in the hands and feet. There are 27 in each hand and 26 in each foot. This means we can move our hands and feet in many different ways. Bones are very strong and very light. If a person weighs 100 kilograms, only about 15 kilograms of this is bone.

腿的顶部是股骨。 这是人体最长、最大、最强壮的骨头。 当人们站立、行走或跑步时，他们所有的重量都落在这块骨头上。 超过50%的人的骨头都在手和脚上。 每只手有27个，每只脚有26个。 这意味着我们可以用许多不同的方式移动我们的手和脚。 骨头很结实，也很轻。 如果一个人体重100公斤，其中只有15公斤是骨头。

But what happens to bones when people die? Well, sometimes bones are not destroyed for a long time, maybe for millions of years. Special scientists called paleontologists study old bones and teeth. They ask questions like these: Have all the skull bones joined together? (This tells them the person's age.) What are the teeth like? (This tells them about what the person ate.) How long is the femur? (This bone is about a quarter of a person's height, so they can guess how tall the person was.) Bones can be the key to the secrets of history!

但是人死后骨头会怎么样呢？ 有时候骨头很长时间都没有被破坏，可能是几百万年。 被称为古生物学家的特殊科学家研究古老的骨骼和牙齿。 他们会问这样的问题：所有的头骨都连在一起了吗？ （这可以告诉他们这个人的年龄。）牙齿是什么样子的？ （这会告诉他们这个人吃了什么。）股骨有多长？ （这块骨头大约是一个人身高的四分之一，所以他们可以猜测这个人有多高。）骨头可能是揭开历史秘密的钥匙！

CHAPTER 2 Dinosaur Bones WERE DINOSAURS BIG OR SMALL, FAST OR SLOW? DID THEY LIVE ALONE OR IN FAMILIES? Today, dinosaurs are everywhere: but only in books, movies, and museums. Real dinosaurs lived in our world between 65 and 230 million years ago. That's about 62 million years before the earliest humans. So how do we know so much about them? When an animal dies, the soft parts of its body are destroyed by nature. But sometimes the hard parts, like the skeleton and the teeth, are not destroyed. This happens when the animal's bones are covered quickly by rock. If the bones stay under this rock for a long time, they become fossils. And scientists can study fossils millions of years later!

恐龙的骨头恐龙是大还是小，是快还是慢？ 他们是独自生活还是与家人一起生活？ 今天，恐龙无处不在：但只是在书、电影和博物馆里。 真正的恐龙生活在6500万到2.3亿年前。 这比最早的人类早了6200万年。 那么我们是怎么知道这么多的呢？ 当动物死亡时，它身体的柔软部分被大自然破坏了。 但有时坚硬的部分，如骨骼和牙齿，不会被破坏。 当动物的骨头很快被岩石覆盖时，就会发生这种情况。 如果骨头在岩石下呆了很长时间，它们就会变成化石。 科学家们可以在数百万年后研究化石！

The first dinosaur fossils were probably discovered thousands of years ago, but people didn't know what they were. The Chinese thought they were dragon bones, and they used them in medicine. And in England in 1676, an Oxford University teacher found a very big leg bone, but he believed it belonged to a giant. In 1841, the British scientist Richard Owen gave the name "dinosaur" to a group of animals. From his studies of bones, he showed that they all had the same kind of pelvis and straight legs (a bit like the human pelvis and legs today). He took the name from the Greek language: deinos meaning "terrible" and sauros meaning "lizard."

第一批恐龙化石可能是在几千年前发现的，但人们不知道它们是什么。 中国人认为它们是龙骨，并将其用于医药。 1676年，一位牛津大学的老师在英国发现了一块非常大的腿骨，但他认为它属于一个巨人。 1841年，英国科学家理查德·欧文给一群动物取名为“恐龙”。 通过对骨头的研究，他发现它们都有相同的骨盆和直腿（有点像今天人类的骨盆和腿）。 他从希腊语中取了这个名字：deinos意为“可怕的”，sauros意为“蜥蜴”。