四六级

　　在英语六级考试听力备考中，听力成绩的提高凭借的是平时大量的练习。小编帮大家准备了英语六级听力练习题系列，这是2017年6月六级备考：六级听力复习题72，希望对大家2017年6月英语六级考试备考有帮助。

　　2017年6月英语六级听力备考：听力练习题大全

2017年6月六级备考：六级听力复习题72.mp3

　　六级听力短文试题选项：

　　29.

　　A. The quicker it vibrates, the greater the frequency of sound it produces.

　　B. The slower it vibrates, the higher the frequency of sound it produces.

　　C. The quicker it vibrates, the lower the frequency of sound it produces.

　　D. The frequency of sound it produces is not in proportion to the speed it vibrates.

　　30.

　　A. Those with frequencies lower than 20 hertz.

　　B. Those with frequencies about 21,000 hertz.

　　C. Those with frequencies lower than 20,000 hertz.

　　D. Those with frequencies higher than 20,000 hertz.

　　31.

　　A. A bat caught the insect in midair and ate it.

　　B. Dolphin's clicking sounds bounced off the fish and back to it.

　　C. A person heard an echo when he shouted into the valley.

　　D. A dog heard his owner's whistle because he used ultrasound.

　　六级听力短文原文：

　　Objects that are vibrating make sounds. Rhythmicsound vibrations produce sound waves which travelin every direction. The frequency of a sound is thenumber of waves that pass a given point eachsecond. [29]The more rapidly an object vibrates, thegreater the frequency of sound it makes. Frequencyis measured in hertz. One hertz equals one soundwave per second. The frequency of sound determines the degree of highness or lowness ofthe sound. A high-pitched sound has a higher frequency than a low-pitched sound. [30]Humans hear sounds that have frequencies from about 20 hertz to 20,000 hertz. Soundwith a frequency higher than 20,000 hertz is called ultrasound which is too high-pitched forhumans to hear. However, many animals can hear ultrasound. Bats can hear higher soundsthan any other animal. Some can hear up to 210,000 hertz. Bats send out lots of high-pitchedsqueaks and then listen to the echoes bouncing off things like insects. The shorter the timeinterval between the squeak and the echo, the closer they are to the insect. [31]Using soundto find or "see" things is called echolocation. Another animal that uses ultrasound is the dolphin.Dolphins can hear sounds up to about 150,000 hertz. Dolphins use sound waves to find foodunderwater. [31]They make clicking sounds that hit whatever is around them and then bounceback to the dolphins. Dolphins can send as many as 2,000 clicks per second. Dolphins'ultrasound ability is so sensitive that they can detect small fish from 10 feet away.

　　Questions 29 to 31 are based on the passage you have just heard.

　　29. What is the relationship between the vibration of an object and the frequency of itssound?

　　正确答案：A

　　解析：细节题。短文提到，物体振动得越快，它制造的声音频率就越高。A为原文中the more...the greater结构的同义表达，故为正确答案。B与C意思相同，可同时排除；D明显与原文内容相冲突。

　　30. What sounds can humans hear?

　　正确答案：C

　　解析：细节题。文中提到，人类可以听见频率在20赫兹到2万赫兹之间的声音。由此可知，C为正确答案。

　　31. According to the speaker, what is the phenomenon of echolocation?

　　正确答案：B

　　解析：细节题。文中提到，用声音来找或看东西被称为“回声定位法”。之后，短文以海豚为例说明“回声定位法”：海豚会发出尖利的声音，这种声音会撞击到它周围的任何物体，然后通过声波形式再传回到海豚处。通过这种方法，海豚可以找到离自己10英尺以内的小鱼。蝙蝠只是利用回声定位原理“找到”食物，但并非caught或ate，所以可排除强干扰项A。

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　　2017年6月英语六级听力备考：听力练习题大全

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