TED演讲:怎样选择适合你的防晒霜(1)

 　　Sunscreen comes in many forms, each with its own impacts on your body and the environment. 防晒霜有很多种，每种对你的身体和环境影响各有不同。

　　With so many options, how do you choose which sunscreen is best for you? 有了这么多的选择，你如何选择最适合你的防晒霜？

　　To answer that question, we first have to understand how sunscreens work. 要回答这个问题，我们首先要了解防晒霜是怎么起作用的。

　　Sunlight is composed of electromagnetic waves and is our primary source of ultraviolet radiation,  阳光由电磁波构成的，是我们紫外线辐射的主源，

　　which has a shorter wavelength¹ than visible light and carries more energy. 其具有比可见光更短的波长并携带着更多的能量。

　　UVA, UVB, and UVC are classified according to their wavelengths². UVA，UVB和UVC是根据其波长来分类的。

　　Short wavelength UVC never reaches the Earth's surface, but UVB and UVA do. 短波长的UVC永远不会到达地球表面，但UVB和UVA可以。

　　Medium wavelength UVB rays can enter the skin's superficial layers and long length UVA rays can penetrate³ into the deeper layers. 中等波长的UVB射线能进入皮肤的浅层，长波长的UVA射线可以渗透到更深的皮肤层。

　　UVB in small amounts actually helps us make vitamin D, which enables our bodies to build and maintain strong bones. 少量UVB实际上可以帮助我们制造维生素D，使我们构建身体和保持强健的骨骼。

　　However, prolonged exposure to UVA and UVB can damage DNA⁴, age your skin, and promote the development of potentially deadly skin cancer. 但是，长期暴露于UVA和UVB之中会破坏DNA，皮肤老化，激发潜在致命皮肤癌的发展。

　　Sunscreen protects your skin either physically⁵ by deflecting⁶ UV rays with an inorganic⁷ blocker like zinc⁸ oxide⁹ or titanium dioxide,  防晒在物理上通过像氧化锌或二氧化钛的无机阻断剂来偏转紫外线从而保护肌肤，

　　or chemically by using carbon-based compounds to absorb UV photons that are then harmlessly dissipated as heat. 或在化学上通过使用碳基化合物来吸收紫外线光子，随后无害的作为热量耗散。

　　So, what differentiates¹⁰ one sunscreen from another? 那么，从什么来区分防晒呢？

1 wavelength   

n.波长

参考例句：

• The authorities were unable to jam this wavelength.当局无法干扰这一波长。
• Radio One has broadcast on this wavelength for years.广播1台已经用这个波长广播多年了。

2 wavelengths   

n.波长( wavelength的名词复数 )；具有相同的/不同的思路；合拍；不合拍

参考例句：

• I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话，因为我们俩完全不对路。 来自《简明英汉词典》
• Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句

3 penetrate   

v.透(渗)入；刺入，刺穿；洞察，了解

参考例句：

• Western ideas penetrate slowly through the East.西方观念逐渐传入东方。
• The sunshine could not penetrate where the trees were thickest.阳光不能透入树木最浓密的地方。

4 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

5 physically   

adj.物质上，体格上，身体上，按自然规律

参考例句：

• He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
• Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。

6 deflecting   

（使）偏斜， （使）偏离， （使）转向( deflect的现在分词 )

参考例句：

• A variety of mechanical surfaces have been employed for deflecting the exhaust jets of solid-propellant rockets. 人们已经用过各种类型的机械控制面来偏转固体推进剂火箭的排气流。
• If she made a leading statement, he was expert deflecting her into more impersonal channels. 只要她一开口，他就会巧妙地把她的话题转到与个人无关的问题上去。

7 inorganic   

adj.无生物的；无机的

参考例句：

• The fundamentals of inorganic chemistry are very important.无机化学的基础很重要。
• This chemical plant recently bought a large quantity of inorganic salt.这家化工厂又买进了大量的无机盐。

8 zinc   

n.锌；vt.在...上镀锌

参考例句：

• Brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。
• Zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。

9 oxide   

n.氧化物

参考例句：

• Oxide is usually seen in our daily life.在我们的日常生活中氧化物很常见。
• How can you get rid of this oxide coating?你们该怎样除去这些氧化皮？

10 differentiates   

区分，区别，辨别( differentiate的第三人称单数 )； 区别对待； 表明…间的差别，构成…间差别的特征

参考例句：

• This genus of plants differentiates into many species. 这种植物可分为许多种类。
• Our fax machine differentiates between an incoming fax signal and a voice call. 我们的传真机能区分接收传真信号和语音信号。