TPO66听力Lecture2听力原文+题目+答案+MP3下载

TPO66听力Lecture2听力原文+题目+答案+MP3下载

TPO66听力原文如下：

Listen to part of a lecture in a marine biology class.

So we'll continue today with the topic of fish movement and we'll focus on the role of fins. You can think of fins pretty much like the arms and legs of humans.It's what allows movement,basically.But as we'll see,they also do a lot more.Before we go on with the function of specific fins,I'll just say a few general remarks so you get an overall picture. Fins are mainly used for moving the fish forward,for propulsion,as it's called.But they are also needed for stability,steering and braking.

That's right.Fish have to have a way to put on the brakes too. Now,some fish are so fast they are not good at stopping even with their fins.Requiem sharks for example. Well,you know how sharks are built for speed,but these requiem sharks have difficulty stopping.They are unable to brake themselves efficiently so they must take sharp turns in order to slow down or stop.Because of this brake problem,requiem sharks avoid swimming into coral reefs.Coral reefs are usually crowded,don't allow a lot of space for large fish to take sharp turns.So these sharks roam around the outside of the coral reefs. Uh,fish lives in a three-dimensional world,you know,with forces pushing and pulling it in all directions.

The forces I'm referring to are gravity,which pulls the fish downward,buoyancy, which holds it up in the water,and something called drag. Now,drag means to slow down,to impede movement.It's a term that applies to the effect of the force acting on any object moving through a fluid,or through air.So for instance the force of air on an airplane.Drag acts to pull the airplane in the opposite direction to the direction of motion.Well,all of these forces,gravity,buoyancy,and drag could be potentially dangerous for fish if it weren't for the fact that they have...yup,you guess it!Fins! So fins allow fish to keep from rolling or flipping over.They stabilize the fish's head.Fins are crucial for determining the speed at which fish travel,to change direction.In a word,fins allow fish to maneuver efficiently through the water.

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TPO66听力题目，一共有6道题，具体如下：

1. What is the main purpose of the lecture?

A. To explain why people sleep at night rather than during the day

B. To discuss the problems caused by a lack of sleep

C. To explain why muscles in the body need sleep

D. To explore benefits that are provided by sleep but not by regular rest
 

2. Why does the professor mention that sleep is a risky behavior?

A. To suggest that resting while awake is better than sleeping

B. To indicate how important the benefits of sleep must be

C. To explain why many animals sleep during the day

D. To explain why birds sleep less than mammals
 

3. According to the professor, why is the sleep of dolphins unusual?

A. Their sleep is interrupted whenever they need to come up for air

B. They can move around while they are asleep

C. In every dolphin group only half of the dolphins are asleep at any given time

D. Their brains show no activity during sleep
 

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