阅读理解；根据其内容，选择正确*或完成阅读任务。Oneofthemostinterestingproject...

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阅读理解；根据其内容，选择正确*或完成阅读任务。

One of the most interesting projects in oceanography(海洋学) is the work of mapping the ocean floor. Only a very small part of it has been mapped was not important when only surface ships sailed the world’s oceans, But it can mean the difference between life and death to men in submarines（潜艇）.

Long ago there was only one way to find out how deep the ocean was .A seaman could throw a weighted rope over the side of his ship. Then he pulled the rope up after it had reached the bottom. But this was not a very exact way of measuring.

In the twelfth century a better way was found. Sound was used to measure the ocean. An American Navy ship sailed the ocean to make an experiment. Seamen dropped a number of devices that would give out a loud noise when they hit the bottom. And a device had been invented measured the time it took for the sound to reach the ship helped oceanographer map the ocean floor.

Underwater photography is also important in mapping parts of the ocean floor. With the new methods that have been perfected, cameras can take pictures of the underwater valleys even in color.

ing the ocean floor is the most important to people＿＿ .

A. on ships B. in boats C. in the sea D. in submarines

2. Which way was used to measure the depth of the ocean in the past?

A. Using a weighted rope B. Using a seaman

C. Using a boat D. Using sound

3. What did the seamen use when they did the experiment?

A. Stones B. Instruments C. Devices D . Ropes

can know from the last paragraph that＿.

A ra is the only perfect way of mapping the ocean floor.

B. camera will take the place of any other instrument.

C. camera can map any part of the ocean floor.

D. camera is one of the new ways to map the ocean floor.