A remarkable variety of insects live in this planet More species of insects exist than all other animal species together. Insects have survived on earth for more than 300 million years, and may possess the ability to survive for millions more.

Insects can be found almost everywhere -- on the highest mountains and on the bottom of rushing streams, in the cold South Pole and in bubbling hot springs. They dig through the ground, jump and sing in the trees,and run and dance in the air. They come in many different colors and various shapes. Insects are extremely useful to humans, pollinating (授粉)our crops as well as flowers in meadows, forests, deserts and otherareas. But licks and some insects, such as mosquitoes and fleas, can transmit disease.

There are many reasons why insects are so successful at surviving. Their amazing ability to adapt permits them to live in extreme ranges of temperatures and environments. The one place they have not yet been found to any major extent is in the open oceans. Insects can survive on a wide range, of natural and artificial foods—paint, pepper, glue, books, grain, cotton，other insects, plants and animals Because they are small they can hide in tiny spaces.

A strong, hard but flexible shell covers their soft organs and is resistant to chemicals, water and physical impact. Their wings give them the option of flying away from dangerous situations or toward food or males. Also, insects have an enormous reproductive capacity: An African ant queen can lay as many as 43,000 eggs a day.

Another reason for their success is the strategy of protective color. An insect may be right before our eyes, but nearly invisible because it is cleverly disguised like a green leaf, lump of brown soil, gray lichen (青苔),a seed or some other natural object Some insects use bright, bold colors to send warning signalsthat they taste bad,sting or are poison.Others have wing patterns that look like the eyes of a huge predator, bitter-tasting insects; hungry enemies are fooled into avoiding them.

练习题：

Choose correct answers to the question:

1.Insects can be found in large amounts in the following places EXCEPT _____.

A.on the mountains with little air

B.in the cold polar areas

C.in the hot desert areas

D.in the open oceans

2.Insects protect themselves from chemicals by _______

A.hiding in tiny spaces

B.having a strong shell

C.flying away when necessary

D.changing colors or shapes

3.Some insects disguise like natural objects so as to ______

A.frighten away their enemies

B.avoid being discovered

C.send warning signals

D.look bitter-tasting

4.The passage mentions that insects ______.英语四级准考证号忘了怎么办

A.can be found in any extreme environments

B.have survived longer than any other creatures

C.can be fed on any natural or man-made foods

D.are important for the growth of crops and flowers

5.The passage is mainly about ______

A.how insects survive in different places

B.why insects can survive so successfully

C.what insects can do to the environment

D.where insects can be found in quantity

1.[D] 事实细节题。本题考查对复合句的理解。本题涉及两个段落，第2段及第3段都提及昆虫大量生长的地方，第3段第3句中的The one place指出了答案。

2.[B] 事实细节题。本题考查对复杂句的理解。第4段第1句指出了答案。protect…from…是对resistant to的同义替换。

3.[B] 推理判断题。本题考查对长句的理解。最后一段第2句中的nearly invisible表明昆虫伪装是为了不被发现，因此B为正确选项。其他选项虽然都是昆虫伪装的目的，但都与伪装成自然物体无关。

4.[D] 推理判断题。本题考查对含有分词结构句子的理解。根据第2段倒数第2句中的useful及分词结构pollinating可推断昆虫对植物的生长有益处。选项A、B、C中都有any,过于绝对。由第3段第2、3句可知选项A不对。文章虽在开头指出昆虫存活的年代久远，但全文未提到它是存活时间最长的生物，所以选项B错误。至于昆虫的食物，第3段倒数第2句有提及,但只是a wide range of,由此可排除选项C。

5.[B] 主旨大意题。本文前两段首先描述了昆虫生存了很长的时间，并能在各种地方生长，然后引出文章要讨论的重点，即昆虫为什么能成功存活。第3段第1句为本文的中心句，因此本题正确选项为B。