听力文摘：为什么有些人是双关节?

Can you bend your thumb backwards¹ until it touches your wrist?

你是否能将大拇指向后弯曲直至其触碰到手腕部位？

If you join your hands behind your back, can you lift them over your head without letting go?

你将双手在背后紧握，是否能够将其举过头顶而不松手？

If you can, you might be what some people call double-jointed.

如果你能做到，那么你可能拥有双关节。

But, A Moment of Science wonders, how could anyone have double joints³?

但是，《科学一刻》想知道，一个人怎么可能拥有双关节呢？

Double-jointed people don't really have two joints.

所谓双关节的人并非真正拥有两个关节。

Any joint², such as the thumb joint or the shoulder, can be called double-jointed if the tendons and ligaments surrounding the joint allow a wider range of motion than is usual.

任何关节，如肩关节或拇指关节，若围绕其四周的韧带和肌腱的活动范围超出平常，则可被称为双关节。

Joints are created whenever 2 adjacent bones meet.

关节是两骨相接而形成的。

They have fibrous bands of connective tissue called ligaments that stabilize⁴ the joint.

他们含有被称为韧带的结缔组织纤维带，韧带能够稳定关节。

Connective tissues also form the tendons that join the bones to the muscles.

结缔组织同时也组成了连接肌肉与骨头的肌腱。

Ligaments and tendons usually restrict the movement of the joint, but in some people, these normally restrictive tissues can be quite flexible and allow the extra movement we call double-jointed.

韧带与肌腱通常会限制关节的活动，但是对于某些人来说，这些结缔组织非常灵活，能做出更大范围的运动，也就是我们所称的双关节。

Practice can increase a joint's natural flexibility⁵ just the way stretching can increase your muscles'flexibility.

通过锻炼能增加关节的自然柔韧性，正如伸展运动可加强肌肉的柔韧性一样。

While flexible joints are very useful to contortionists, some joints can become so loose that they are unstable⁶.

灵活的关节对柔术演员来说至关重要，但他们的一些关节可能会变得十分不稳固。

This allows the bones of the joint to slip out of their sockets⁷ and can be very damaging.

这很容易造成关节脱臼，对身体造成很大的伤害。

Strengthening the muscles around the joint can stabilize it and still allow you to show off your trick joint at parties.

加强关节周围肌肉的锻炼能够使关节稳固，并且你依然可以在各式派对上炫耀你的小把戏。

1 backwards   

adv.往回地，向原处，倒，相反，前后倒置地

参考例句：

• He turned on the light and began to pace backwards and forwards.他打开电灯并开始走来走去。
• All the girls fell over backwards to get the party ready.姑娘们迫不及待地为聚会做准备。

2 joint   

adj.联合的，共同的；n.关节，接合处；v.连接，贴合

参考例句：

• I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤，肩膀脫臼了。
• We wrote a letter in joint names.我们联名写了封信。

3 joints   

接头( joint的名词复数 )； 关节； 公共场所（尤指价格低廉的饮食和娱乐场所） （非正式）； 一块烤肉 （英式英语）

参考例句：

• Expansion joints of various kinds are fitted on gas mains. 各种各样的伸缩接头被安装在煤气的总管道上了。
• Expansion joints of various kinds are fitted on steam pipes. 各种各样的伸缩接头被安装在蒸气管道上了。

4 stabilize   

vt.（使）稳定，使稳固，使稳定平衡；vi.稳定

参考例句：

• They are eager to stabilize currencies.他们急于稳定货币。
• His blood pressure tended to stabilize.他的血压趋向稳定。

5 flexibility   

n.柔韧性，弹性，（光的）折射性，灵活性

参考例句：

• Her great strength lies in her flexibility.她的优势在于她灵活变通。
• The flexibility of a man's muscles will lessen as he becomes old.人老了肌肉的柔韧性将降低。

6 unstable   

adj.不稳定的，易变的

参考例句：

• This bookcase is too unstable to hold so many books.这书橱很不结实，装不了这么多书。
• The patient's condition was unstable.那患者的病情不稳定。

7 sockets   

n.套接字，使应用程序能够读写与收发通讯协定(protocol)与资料的程序( Socket的名词复数 )；孔( socket的名词复数 )；（电器上的）插口；托座；凹穴

参考例句：

• All new PCs now have USB sockets. 新的个人计算机现在都有通用串行总线插孔。
• Make sure the sockets in your house are fingerproof. 确保你房中的插座是防触电的。 来自超越目标英语 第4册