A pair of beavers will build a dam, using branches, mud and stones, across a river. The water held back by the dam flows over the bank on either side of the river, flooding the nearby ground and forming a pond. At some point in the pond the beavers then build their home, which is called a lodge. This consists of a cone-shaped(锥状的) pipe of branches and sticks of two to six feet in length held together with mud and stones, the top of which projects above the waterline. It serves as a shelter from the bad weather, a safety from enemies and a base for food supplies to be drawn upon in winter.

From an engineering point of view the lodge could hardly be improved. Not only does it contain a central room just above water level, which is accessible only through underwater tunnels, but it also has “walls”, one or more escape tunnels and an air hole at the top, which controls the temperature inside and gives air-conditioning. It is altogether a clever piece of construction, with all modern conveniences. It is, in fact, better protected against the effects of flooding than many human houses.

Trees are essential to beavers. They eat the bark on the upper branches. But they must first fell the trees, using their four front teeth. With these sharp tools, it takes only a few minutes to cut down a tree.

The engineering skill of beavers is to a large extent a result of their ability to use their front paws as hands. A female will carry her young held under her chin(下巴) with her front paws, walking on her hind legs. A similar method is used by all beavers when transporting stones or mud, although they also carry such materials on their broad flat trails. The fore-paws are also used for digging and for dragging heavier pieces of wood.

【1】Which of the following pictures best illustrates the beaver’s lodge?

A. B.

C. D.

【2】Which of the following sentences is Not the reason why trees are important to beavers?

A. They live on the barks on the upper branches of trees.

B. They use trees’ branches to build dams.

C. They build their lodge with the branches.

D. They us branches to transport mud and stones.

【3】The underlined word “fell” in Paragraph 4 probably means ________.

A. move awayB. cut downC. cut upD. move about

【4】This text is mainly about ________.

A. the beaver’s lodge

B. the beaver’s engineering skills

C. the beaver’s dam

D. the beaver’s intelligence

【答案】

【1】C

【2】D

【3】B

【4】B

【解析】

试题分析：文章介绍了大自然的建筑师河狸和给人类的启示。

【1】C 推理判断题。根据第二段which is called a lodge. This consists of a cone-shaped(锥状的)pipe of branches and sticks of two to six feet in length held together with mud and stones, the top of which projects above the waterline.可知，这小坝是锥形的，且高出水平线，故选C图。

【2】D 细节理解题。根据Trees are essential to beavers. They eat the bark on the upper branches. But they must first fell the trees, using their four front teeth. With these sharp tools, it takes only a few minutes to cut down a tree.

可知，河狸吃树皮，用树枝搭他们的小屋，而不是用它来运送泥土和石块，故选D。

【3】B 词义推测题。根据But they must first fell the trees, using their four front teeth. With these sharp tools, it takes only a few minutes to cut down a tree.可知，河狸通过牙齿把树砍倒，此处fell意为“cut down”，故选B。

【4】B 主旨大意题。根据The engineering skill of beavers is to a large extent a result of their ability to use their front paws as hands.和整篇文章可知，全文主要讲述了河狸的建筑技巧，故答案为B。