Tinymonitoringdeviceshavebecomeanincreasinglycommonwa...

问题详情：

   Tiny monitoring devices have become an increasingly common way for scientists to study elusive animals that are difficult to track on a day-to-day basis. However, now it seems that smart. seals have caught on to the trick and are using it to their advantage to catch fish!

    To find out if that is true, a team of researchers from the University of St. Andrews in Scotland selected a group often young grey seals that had neither encountered the ocean nor been exposed to any kind of acoustic（声音的）tags. The researchers then placed the seals one at a time, inside a pool that contained 20 foraging boxes, only two of which housed fish — one with tags and the other without.

Each seal was allowed to explore the boxes twenty separate times. In order to ensure that mammal was not depending on its memory, the fish were moved to different boxes each time. At first, there was no difference in the amount of time it took the seals to discover the tagged and untagged fish. However, after they had been in the pool a few times, they started locating the tagged fish much faster.

    To confirm that this indeed was the case, there searchers conducted a second experiment using two boxes — one with pieces of fish and the other with just acoustic tags. Sure enough, the seals were all attracted to the one that was sending out signals.

    While this experiment involved only seals, the researchers believe that other marine mammals may also be using the information to catch prey. Sadly, predators like sharks that have been tagged by scientists may be negatively affected, as pings they emit could warn their prey of their presence. Besides potentially messing up nature’s food chain, the “dinner bell” effect of the acoustic tags could also mean that the conclusions reached by previous fish studies may not be correct. Now that the secret is out, scientists will have to come up with another way to conduct their studies — one that is not detectable by the crafty marine animals.

28. What does the underlined part “the trick” in Paragraph 1 refer to?

    A. Attaching tiny monitoring devices to sea animals.

    B. Following the sound that fish make.

    C. Tracking sea animals on a day-to-day basis.

    D. Looking for ways to catch fish.

29. What is implied about the ten young grey seals?

    A. They have acoustic tags attached to them.

    B. They have better hearing than normal seals.

    C. They have been trained to recognize acoustic tags.

    D. They were not born in the ocean.

30. After doing the two experiments the researchers most probably concluded that ________.

    A. it’s really easy for seals to find their prey

    B. seals can be easily fooled by acoustic tags

    C. seals are much cleverer than most of the other sea animals

    D. seals can really make use of the acoustic signals to prey

31. The researchers seem to believe that sharks tagged by scientists ________.

    A. may benefit from the tags            B. may attract seals by mistake

    C. may find it hard to find prey          D. may be annoyed by the emitted pings

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