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  3. HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD (1) Scientists have discovered that animals are experts at exploiting weat

HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD (1) Scientists have discovered that animals are experts at exploiting weat

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问题                                             HOW ANIMALS IN RAIN FORESTS MAKE THEMSELVES HEARD
    (1) Scientists have discovered that animals are experts at exploiting weather conditions and the physical conditions of their environments so that they are heard or not heard, and seen or not seen. The species living in rain forests must engineer their calls to accommodate all of the obstacles, such as leaf cover, that can deflect and degrade the sounds intended for a potential receiver. Over, short, loud bursts of sound tend to be more effective than longer calls at cutting through the dense foliage.
    (2) There is no natural environment on Earth noisier than a virgin rain forest. In the Peruvian rain forest, every species has developed clever or remarkably sophisticated strategies to ensure that its voice is heard. The noise creates a real challenge for the smaller residents, such as male tree crickets, which need to get the attention of females, often from a relatively long distance. Some species of crickets maximize the volume of their calls by chewing a hole in the middle of a leaf to create a sound baffle, similar to a stereo speaker. The leaf functions as a speaker cabinet, with the cricket in the center acting as the speaker.
    (3) A species of tree frog in Borneo has an inventive approach to getting its mating call heard over the noise. Mataphrenella sudana, which is only an inch long, has learned to exploit the sound properties of a water-filled hole in a tree in the same way that a person uses resonance, the intensification and enrichment of a sound by added vibration, in the shower to sing like a professional performer. The frog searches for a suitable hole and then partially submerges itself in the water. Its forte is the ability to adjust the frequency of its call to the size of the hole and play the tree like a musical instrument. As it sits in the hole, it begins vocalizing at different frequencies until it hits the one note that makes the hole and tree resonate.
    (4) The time of day affects how sound travels in any environment, and this fact is not lost on animals and insects. Early morning and late evening produce conditions that allow sound to travel greater distances than during the middle parts of the day. Sound travels best at night, which is why the rain forest is so wonderfully noisy between dusk and dawn. For species that sleep at night, dusk and dawn are their windows of opportunity to get the best resonance and distance out of a signal. This is why animals, especially birds, tend to be more active and noisy in the early morning and late evening. The British call the phenomenon of birds singing in the early morning the dawn chorus. Because of the superior sound conditions, dusk and dawn are the times to conduct the serious business of attracting mates and defending territories. For predators, it is the best time to track down their noisy prey.
    (5) Another way animals and insects ensure that their calls connect with the intended receivers is by developing their own specialized frequencies, which are determined primarily by the size of their bodies. [A] Recently, a scientist visiting the Peruvian rain forest made an audio tape of a little of the night’s music. [B] When he took the tape back to his lab and analyzed it, he discovered that this seemingly chaotic banquet of sound was actually highly ordered. [C] Each animal and insect is tuned to and calling on its own species-specific frequency, in the same way that radio stations use different signals so that many stations can broadcast at the same time. [D]
    (6) Bernard Krause, a professor at the University of Oregon in Eugene, has found that in older tropical rain forests some species, such as the Asian paradise flycatcher, have become so specialized that their voices occupy several niches of the sound spectrum at the same time, thus laying territorial claim to several audio channels. His recordings from undisturbed rain forests around the world demonstrate a remarkable stability in the combined voices of the residents from year to year. The stability of the ambient sound gives each region a unique sound signature, or fingerprint.
According to paragraph 4, what is a disadvantage of many birds all singing at dusk and dawn?
选项 A、There is more competition from other birds at these times.
B、These are the safest times for birds to sleep.
C、It is easier for predators to locate birds when so many are making noise.
D、There are the best times for birds to find prey.
答案C
解析 本题是事实信息题，问根据第4段，很多鸟在黄昏和拂晓齐鸣的一个坏处。从题干中的birds和dusk and dawn可以定位到第4段最后四句，其中，倒数第2句说的是鸟类在这两个时段呜叫的好处，而最后一句说的是坏处，即这也是捕食者追踪猎物的最佳时机，故C项“很多鸟呜叫时，捕食者更容易发现它们的位置”与文意相符。A项“在这些时段，鸟类的竞争更激烈”，文中没有说在这些时段竞争更激烈，只是指出在这些时段，声音传播的条件更有利，鸟类更活跃更吵闹，这并非不利条件。B项“这些时段是小鸟睡觉最安全的时段”，文章说的是，小鸟在这些时段更活跃，而不是小鸟能更安全地睡觉。D项“是小鸟捕捉猎物的最佳时机”利用第4段最后一句中的prey设置干扰，这里的noisy prey指的是小鸟，而不是它们的猎物，故排除。
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