问题 选择题

生态系统中的能量可以沿着下列哪条链正常流动(  )

A.草→食草昆虫→青蛙→蛇

B.草→吃虫鸟→鼠→青蛙

C.草→兔→食草昆虫→猫头鹰

D.狐→兔→蜘蛛→草

答案

生态系统中的能量由生产者植物通过光合作用固定的太阳能,然后通过动物的取食沿食物链流动,能量在沿食物链的流动过程中会被逐级消耗.

A、该食物链正确的反应了生产者草与消费者食草昆虫、青蛙、蛇之间的吃与被吃的关系,因此能量能够沿该条食物链流动.故符合题意.

B、食虫鸟不能直接以草为食,属于次级消费者,能量不能直接由生产者流动到次级消费者,故不符合题意.

C、兔与食草昆虫都直接以生产者草为食,它们体内的能量直接来自于生产者,因此兔体内的能量不能流动到食草昆虫体内;故不符合题意.

D、生态系统中的能量只能从生产者流向消费者,而不能从消费者流向生产者,故不符合题意.

故选:A

计算题
阅读理解

阅读理解。

     The Great Wall of China is one of Beijing's biggest draws for tourists; despite its fame and ubiquity

in postcards across the world, it rarely fails to attract tourists at the first proper sight.

     Yet the authorities open only certain sections of the wall as fit for viewing, and few get to visit the

unauthorized sections. Fewer still are aware of the existence of at least one part of the Wall that remains

in almost original condition, nearly 1, 500 years after construction of legendary fortification began. But

there's a good reason for this-it's underwater.

     American journalist Steven Schwankert has been diving since age 10. It was through his setting-up

of a diving school that Schwankert came to explore some of lesser-known areas of China's Iakes-and

discovered the underwater Wall under a reservoir.

     "The most fascinating piece of diving I ever did in China must be the Great Wall. I managed to find

out about it via the Internet It wasn't difficult to get to Pan Jiakou in Hebei Province, near the East Qing

Tomb about 4 hours' drive from Beijing. Why do I want to dive the Great Wall? Why do people want to

walk on the Great Wall? It's the same answer."

     There are, however, advantages of visiting the Great Wall in a diving suit over being on foot. The

water acts as a preservative by preventing the kind of mass tourism that has brought trouble on other

parts of the Wall. "Unlike the people who walk in the Wall, we as divers never need to actually touch it.

I've dived twice there, the last time in July. I found that the water then was much deeper than it was

before-13 meters deep.." When he first dived, parts of the Wall were visible above the surface. Now

even the guard tower is completely submerged. "It's better that the Wall is deep under water, as there

are lots of boats coming in and out around that area. Their wave action could potentially damage the

brickwork. So, the deeper, the better."

1. Steven Schwankert is most interested in _____.[ ]

A. collecting photos of the Wall

B. walking along on the Wall

C. diving the underwater Wall

D. visiting some famous lakes

2. What does the underlined word "submerged" in Paragraph 5 most probably mean? [ ]

A. Damaged by water.

B. Washed by water.

C. Preserved by water.

D. Covered by water.

3. What is the topic discussed in the last paragraph?[ ]

A. Advantages of walking on the Great Wall.

B. Advantages of visiting the underwater Wall.

C. The reasons why the Wall is deep under water.

D. The reasons why the underwater Wall is protected.

4. What can we infer from the text? [ ]

A. The underwater Wall will sink deeper year by year.

B. Diving the Wall is popular with divers all over the world.

C. DiVing is a good way to visit the Wall without causing much damage.

D. More and more tourists will come to visit the underwater Wall in China.