Question

    You are walking over the tan-colored（棕褐色的）sand of the empty desert when a rattlesnake appears out of the sand in front of you. Luckily it had warned you of its presence. Imagine if that same snake were moved to a green leafy rainforest. The colors that helped the snake blend into（融合）the desert would make it stand out against the green environment.

This just goes to show you that camouflage（保护色）doesn't work everywhere. Let's take a look at one animal species that is famous for changing over time to stay camouflaged: the peppered moth. Moth collectors in England noted that most peppered moths collected in the early 1800s were light gray peppered with bits of black. Many years later most of the moths collected were almost completely black. What could have caused the more common light colored moth to become rare?

During the 1800s, Europe and America experienced the Industrial Revolution. One of the new fuel sources that were heavily used during this time period was coal. As the trees darkened with soot（煤烟）, the light-colored moths were easier to see. They were eaten by birds more and more, while the rare dark colored moths blended in better on the darker trees. This made them have a higher survival rate and thus they were more likely to pass their dark colored genes onto their children. Over time, the dark colored moths became the more common of the two color forms. Natural selection favored the dark moths, so they were more successful after the trees changed.

Sound a little hard to believe? Well, more changes have come about since these conditions started to reverse（转变）, starting in the 1950s. Then, a Clean Air Act was introduced. Since that time, technology and cleaner burning fuels have started to decrease pollution in the areas where the peppered moth lives. The black soot no longer settles on the trees. As expected, the light peppered moth has recently been more common in the population. This is because it is better camouflaged.

1.What do we know about the rattlesnake in a desert?

A.It almost has no enemies.

B.It attacks travelers often.

C.It stands out against the environment.

D.It is good at making its presence unknown.

2.The underlined word "This" in Paragraph 3 refers "      "

A.the soot-darkened tree

B.the Industrial Revolution

C.dark-colored moths staying camouflaged

D.light-colored moths facing more enemies

3.What did the Clean Air Act bring about?

A.Damage to local ecology. B.More observations of moths.

C.An increase in the variety of moth species. D.A decrease in the number of dark-colored moths.

4.What is the text mainly about?

A.Camouflage in the animal world. B.The battle between two moth species.

C.The influence of the Industrial Revolution. D.An excellent example of environmental adaptation.

Answer

1.D

2.C

3.D

4.D

【解析】

本文是说明文。文章介绍了擅用保护色来伪装自己的胡椒蛾。

1.

细节理解题。根据第一段最后一句：The colors that helped the snake blend into the desert（颜色帮助这种蛇融入了沙漠。）可知，沙漠中的响尾蛇善于让自己的存在不为人所知。故选D。

2.

词义猜测题。由划线词前一句中的while the rare dark colored moths blended in better on the darker trees而稀有的深色蛾则更好地融合在深色的树上。可知，This此处指代“深色胡椒蛾能更好地与周围环境相融合”的情况。选项C“深色胡椒蛾进行伪装”符合题意。故选C。

3.

推理判断题。根据最后一段中的Then, a Clean Air Act… the light peppered moth has recently been more common in the population. 然后，《清洁空气法案》被提出。 从那时起，科技和清洁燃料已经开始减少胡椒蛾生活的地区的污染。 黑色的烟尘不再落在树上。 正如所料，浅色胡椒蛾最近在种群中更为常见。可知，《清洁空气法案》的落地意味着深色胡椒蛾不再能利用保护色伪装自己，其数量锐减。选项D符合题意。故选D。

4.

主旨大意题。第二段Let's take a look at one animal species that is famous for changing over time to stay camouflaged: the peppered moth.（让我们来看看一种动物，它以随着时间的变化而保持伪装而闻名:胡椒蛾。）是全文的主题句，结合全文内容，可知这篇文章介绍了胡椒蛾为适应环境变化所做出的改变——其身体的颜色随着所栖息的树木的颜色的变化而变化。D项“一个很好的适应环境的例子”最能概括本文主旨。故选D。