托福听力真题原文+题目+答案+mp3下载：Tidal currents

托福听力真题原文+题目+答案+mp3下载：Tidal currents

托福听力真题原文如下：

M: Recently, I've been spending some time talking to you about the need to find renewable sources of energy. Well, we've done solar and wind energy. So I thought for today's class we could talk about ways to harvest energy from the sea. Specifically,let's focus on the tidal currents that exist within the ocean.Tidal energy, also called tidal power, is a form of hydropower that converts the energy of tides into electricity or other useful forms of power.A way to get energy from these tidal currents is to use tidal turbines.

As the currents pass through the turbines, the turbines will turn, and this will produce electricity.A tidal turbine look a lot like a windmill, just under the water.And, they actually work in pretty much the same way.The idea isn't that new, ifs been discussed for quite some time now. Recently, we have been able to create materials that car withstand the corrosive damage from salt water during extended submersion.And it makes the use of the turbines more prevalent. So, the total availability of tidal power may be muchhigher than previously assumed, and economic and environmental costs may be brought down to competitive levels.

W:Professor, wait a second.But tidal currents move so slowly, I mean, doesn't wind move a lot faster than water? How could they produce electricity?

M: Good question, well, simply put, water is over hundred times denser than wind is. Even with a slower current, you still have enough force to generate a large amount of power. Actually, a 10 kilometer per hour tidal current generates enough electricity to match a wind current of 300 kilometers per hour.。。。。。余下托福听力真题原文省略！

托福听力真题题目如下：

1.What is the main purpose of the lecture?

（A）To discuss harnessing tidal energy from the ocean (A]

（B）To give details about the available renewable sources of energy

（C）To compare advantages and disadvantages of using tidal energy as a source of energy

（D）To argue that tidal energy is a better source of energy than other renewable SOurces

2.Which of the following is mentioned in the passage to imply that the use of tidal turbines hasn't been popular for a very long time?

(A) They have only been at the discussion stage of development.

(B)The ocean was too corrosive for the machines.

(C) They were too similar to windmills,which were not very reliable.

(D) The development of appropriate methods was severely insufficient.

。。。。。余下托福听力真题题目及答案省略！

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