It’s hard to track the blue whale, which has almost been killed off by commercia

It’shard to track the blue whale, which has almost been killed off by commercialwhaling. Attaching radio devices to it is difficult and visual sightings aretoo unreliable to give real insight into its behavior.

So biologists were delightedearly this year when, with the help of the US Navy, they are able to track aparticular blue whale for 43 days recording its sounds. This was possiblebecause of the Navy’s former top secret system ofunderwater listening devices across the oceans.

Tracking whales is but oneexample of an exciting new world just opening to civilian scientists after thecold war as the Navy starts to share and partly uncover its global network ofunderwater listening system built over the decades to track the ships ofpotential enemies.

Earth scientists announced at anews conference recently that they had used the system for closely observing adeep-sea volcanic eruption for the first time and that they planned similarstudies. Other scientists have proposed to use the network for tracking oceancurrents and measuring changes in the ocean and global temperatures. Differentlayers of ocean water can act as channels for sounds focusing them in the sameway 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 mainreason that even relatively weak sounds in the ocean, especially low-frequencyones, can often travel thousands of miles.

1.The underwater listening system wasoriginally designed _________________.

  A. to trace and locate enemy ships

  B. to observe deep sea volcanic eruptions

  C. to study the movement of ocean currents

  D. to replace the global radio communicationsnetwork

2.The deep-sea listening system makes use of__________________.

  A. the ability of sound to travel at highspeed

  B. the top-level technology of focusingsounds under water

  C. the unique characteristic of layers ofocean water in carrying sound

  D. low-frequency sounds traveling acrossdifferent layers of water

3.What can we infer from the passage?

  A. New radio devices are developed fortracking the blue whales.

  B. Blue whales are no longer endangered withthe new system.

  C. Opinions differ on the use of militarytechnology.

  D. Military technology has great potentialin civilian use.

4.What is the passage chiefly about?

  A. An effort to protect an endangered marinespecies.

  B. The civilian use of a military detectionsystem.

  C. The exposure of a US Navy top-secretweapon.

  D. A new way to look into thebehavior of blue whales.

试题答案

【答案】

1.A

2.C

3.D

4.B

【解析】略