四、阅读理解
Oceans cover about 71 per cent of the earth's surface, but here's a lot we don't know about them. Only about 20 per cent of the seafloor has been mapped (绘图), and the rest 80 per cent is still a secret (秘密) to us. Some scientists even think we only know 10 per cent of the sea animals.
So why do we know so little about the deep sea? Well, getting to the deep water is very difficult and needs high technology (科技). The first navigable submarine (可驾驶的潜水艇) in 1620, for example, couldn't go more than five metres below the surface. In fact, for a long time many scientists didn't even think that there could be any life in the water deeper than 550 metres and didn't see much need to learn about the deep sea. But this changed in 1862 when people found life as far down as 945 metres below sea level (海平面) with the help of a machine. Ten years later, scientists found around 4,700 species (物种) unknown before from the ocean floor.
Now high technology like satellites (卫星) helps us learn more about the deep sea. But why is studying deep sea still so difficult? Well, in deep water, it is freezing (极冷的), everything is completely (完全地) dark, and the pressure (压力) can be over 1,000 times greater than that on the surface.
We have a lot of problems, but it's important to understand the oceans.
They help control (控制) the earth's temperature (温度) and produce half of the oxygen ($O_{2}$) in the air. They can also give us information about weather change. Our future largely depends on learning more about our oceans, so we really need to understand what is going on below the surface.
(
D
) 1. Why are some numbers listed in Paragraph 1?
A. To introduce how important oceans are.
B. To show why we need to learn about sea animals.
C. To tell that oceans cover a large area of the earth.
D. To show that we know just a little about oceans.
(
A
) 2. What helps humans learn more about the deep sea?
A. High technology.
B. Secret species.
C. The clean sea water.
D. Useful information.
(
B
) 3. What does the underlined word "They" in the last paragraph refer to (指的是)?
A. Sea animals.
B. The oceans.
C. The satellites.
D. Many scientists.
(
B
) 4. What can we learn from the text?
A. It is difficult to build a navigable submarine.
B. The oceans have a strong influence (影响) on our future.
C. The oceans have no lives 550 metres below sea level.
D. It is easier to go into the deep sea than we think.
Exercise 2 of Unit 6 of 7B Reading ([
])
