题目内容
It is hard to track the blue whale, the ocean's largest creature, which has almost been killed off by commercial whaling and is now listed as an endangered species. Attaching radio devices to it is difficult, and visual sightings are too unreliable to give real insight into its behavior.
So biologists were delighted early this year when, with the help of the Navy, they were able to track a particular blue whale for 43 days, monitoring its sounds. This was possible because of
the Navy's formerly top-secret system of underwater listening devices spanning the oceans.
Tracking whales is but one example of an exciting new world just opening to civilian scientists after the cold war as the Navy starts to share and partly uncover its global network of underwater listening system built over the decades to track the ships of potential enemies.
Earth scientists announced at a news conference recently that they had used the system for closely monitoring a deep-sea volcanic eruption (爆发) for the first time and that they plan similar studies.
Other scientists have proposed to use the network for tracking ocean currents and measuring changes in ocean and global temperatures.
The speed of sound in water is roughly one mile a second-slower than through land but faster than through air. What is most important, different layers of ocean water can act as channels for sounds, focusing them in the same way a stethoscope (听诊器) does when it carries faint noises from a patient's chest to a doctor's ear. This focusing is the main reason that even relatively weak sounds in the ocean, especially low-frequency ones, can often travel thousands of miles.
The passage is chiefly about______ .
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听力原文：W: Where do you spend your weekend？ For me, movies and restaurants are good places to enjoy myself.
M: That's expensive to me. I'd like to go to party with my friends.
What does the man prefer to do on weekend？
How is the water around the edges of the continents？
听力原文：W: Dr. Steven, I am thinking about changing my major before the end of the freshman year.
M: What are you studying now？
W: I am taking three general courses and American history and American literature this semester. Last semester I took four requirements and freshman French.
M: I believe it's not too late to change your major because you've mainly taken general requirements which all freshmen have to take. Also we have twelve electives so the two literature courses will be included in them, so you can change your major without losing any credit hours.
W: I am very happy to know I am still able to change my major. I am interested in writing newspaper articles, and after finishing my degree I would like to work for some newspaper firm.
M: Oh, I think you will be a good writer.
W: Dr. Steven, when do students start practical training？
M: They don't begin practical training in reporting until the sophomore year. Journalism normally is taken in the freshman year as a general background course.
W: I see. I will take the course next semester. Thank you very much for your help.
M: You're welcome. I look forward to seeing you in my department.
How many courses did the woman take last semester？
Part B
Directions: You will hear four dialogues or monologues. Before listening to each one, you will have 5 seconds to read each of the questions which accompany it. While listening, answer each question by choosing A, B, C or D. After listening, you will have 10 seconds to check your answer to each question. You will hear each piece ONLY ONCE.
听力原文： The sea is the largest unknown part of our world. It covers seventy-one percent of the earth. There is still much to be discovered about this vast blanket of water. If the waters of the ocean could be moved away, the sea floor with its wide valleys, irregular fountains and rivers in the sea would be an unbelievable sight. Around the edges of the continents the ocean floor is flat and the water does not become much deeper for about thirty miles. Where there are high young mountains along the coast, this flat part may be much less than thirty miles. But where rivers flow into the sea, the flat area may extend for hundreds of miles. The region near the continents, where the water is not so deep, is the place where you can find a lot of living creatures and plants. Below these living creatures and plants are the largest known quantities of minerals. At the end of the flat part the sea floor suddenly drops down, forming deep hollows that are shaped like bowls. These huge hollows hold most of the world's water.
How much percent of the earth does the sea cover？
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