Question

It is hard to track the blue whale, the ocean’s largest creature which has almost been killed off and is now listed as an endangered species. Joining radio equipment to it is difficult and observing with human eyes are too unreliable to learn about its behavior.

So biologists were pleased early this year when with the help of the Navy(海军) they were able to track a particular blue whale for 43 days monitoring(监视) its sounds. This was possible because of the Navy’s formerly top-secret system of underwater listening equipment across the oceans. Tracking whales is only one example to show that an exciting new world is opening its window to civilian scientists after the cold war as the Navy starts to share its network of underwater listening system built over the decades to track the ships of potential enemies.

Scientists announced at a news conference recently that they had used the system for closely monitoring a deep-sea volcanic eruption for the first time. It is proposed that the network should be used to track ocean currents and measure global temperatures.

The speed of sound in water is roughly one mile a second--slower than through land but faster through air. Different layers of ocean water can act as channels for sounds conveyed to 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.

1．The passage is chiefly about ___       _.

       A．an effort to protect an endangered marine species

       B．the civilian use of a military detection system

       C．the exposure of a U. S. Navy top-secret weapon

       D．a new way to look into the behavior of blue whales

2．The underwater listening system was originally designed ___    __.

       A．to mark and locate enemy ships

       B．to monitor deep-sea volcanic eruptions

       C．to study the movement of ocean currents

       D．to replace the global radio communications network

3．The deep-sea listening system makes use of _____.

       A．the complex technology of focusing sounds under water

       B．the capability of sound to travel at high speed

       C．the special quality of layers of ocean water in sending out sound

       D．low-frequency sounds traveling across different layers of water

4．According to the passage, sound travels faster through______________.

       A．water than land                                    B．air than land

C．air than water                                      D．land than air

5．It can be learned from the passage that _____.

       A．new radio equipment should be developed for tracking the endangered blue whales

       B．military technology plays an important role in scientific research

       C．civilian scientists will do little without the help of military technology

       D．blue whales are no longer endangered with the use of the new system

Answer 1

BACDB