Question

Nature is full of color, from rainbows and roses to butterfly wings and peacock tails. Even the fruits and vegetables you eat have different colors: blue blueberries, red strawberries, green broccoli, and orange carrots.

Plant and animals often use color to attract attention. The substances responsible for these colors belong to a class of chemical called antioxidants(抗氧化物). Plants make antioxidant to protect themselves from the sun's ultraviolet(紫外线)light.

Ultraviolet light causes chemicals called free radicals(自由基)to form within plant cells. They can destroy parts of plant. Free radicals also have damaging effects on human beings. Some of these effects like wrinkled skin can be seen. The damage is caused by the free radicals attacking cells in our bodies. Certain cancers and heart disease are linked to free radicals.

Our bodies have natural defences for fighting off free radicals. While we are young, our defences are pretty strong. However, they get weaker as we get older. The body’s built-in defences can only go so far without extra help.

The key to fighting free radicals with fruits and vegetables is to mix and match colors. It’s like sunscreen(防晒霜)for the inside of your body. Go for a range of very bright colors. Colorful foods contain hundreds of healthy chemicals not found anywhere else.

Research into how chemicals in blueberries affect the brain's function in rats suggests that these chemicals may help our own brains work more efficiently.

Don't just blame the sun. Ultraviolet light isn't the only source of free radicals. If you breathe polluted air such as smog, automobile exhaust(废气), or wasted gas from a factory, you take in chemicals that also cause such damage. And, the body itself produces free radicals as it processes food.

1.Which of the following NOT true?

A．Antioxidants are responsible for plant colors.

B．Plants use color to attract attention.

C．Antioxidants help free radicals to attack plants.

D．Antioxidants can protect plants from ultraviolet light.

2.In which order do the following facts occur?

a .Wrinkled skin can be seen

b .Ultraviolet light causes free radicals to form

c .Free radicals damage cells in our bodies

d .The sun gives out ultraviolet light

A．a,b,c,d                            B．d,b,a,c

C．c,a,d,b                            D．d,b,c,a

3. We need extra help for fighting off free radicals from fruits and vegetables because ____.

A．our defences get weaker as we get older

B．our bodies’ defences are not natural

C．we are too young to defend ourselves

D．our bodies’ built-in defences can only go away

4.Which of the following can NOT cause free radicals to form?

A．Ultraviolet light from the sun

B．Colorful food

C．Polluted air

D．The body itself

Answer

1.C

2.D

3.A

4.B

【解析】

试题分析：这篇文章讲述了太阳的紫外线、烟雾、汽车的排气、工厂的废气等都可造成自由基的生成，自由基会破坏人体细胞，各种颜色的食物是帮助我们抗自由基的有效方法。

1.

2.Ultraviolet light causes chemicals called free radicals(自由基)to form within plant cells. They can destroy parts of plant. Free radicals also have damaging effects on human beings. Some of these effects like wrinkled skin can be seen.内容可知事情发生的先后顺序是：先是太阳释放出紫外线，然后紫外线造成自由基的生成，接着自由基破坏我们身体的细胞，最后皮肤起皱纹，故选D。

3.

4. 细节理解题。根据文章最后一段Don't just blame the sun. Ultraviolet light isn't the only source of free radicals. If you breathe polluted air such as smog, automobile exhaust(废气), or wasted gas from a factory, you take in chemicals that also cause such damage. And, the body itself produces free radicals as it processes food.说明太阳、被污染的空气以及我们自己的身体都会释放出自由基。而根据文章第五段可知各种颜色的食物是帮助我们抗自由基的，这些食物里有很多健康的化学物质帮助我们。因此选A。

【名师点睛】

本文5.

1．四个选项中的信息集中在一、二个句子里。这种是非题比较容易做。只要找到相关句，细细读一下就不难选定正确答案。

2．四个选项中的信息集中在一段里。这样查读的范围要大一些，但还是比较容易的。验证一个，排除一个，答案就出来了。

3．四个选项中的信息分散在全文。这种是非题就比较难做，因为要化较多的时间去找各个相关句，一一去查证。一般说来，应首先把四个选项都看一遍，根据第一遍读的印象和基本常识，尽可能先排除掉一、二个，以减少查的选项。实在排除不了，需要到文章中去一一查证的，次序也应从易到难，即从印象最深的，相关句最易找的，最容易证实的那个选项开始查。

由于时间关系，要到全文中去一一查证四个选项，效率太低。因此我们还可以首先对所有选项作一分析，根据常理，根据自己的知识结构，看看哪一选项最有可能是答案。如问哪一个true，就把四个中最可能正确的一项挑出来首先去查证；如问哪一个NOT true，就把四个中最可能是错误的一项挑出来首先去查证。用这一方法，最多查证两项，答案就会出来。

考点：考查科普说明文阅读