Passage Three
For three groups of explorers formed by college students and young white collars,it started out as a wonderful trip. They were enjoying themselves exploring the Inner Mongolian desert. [32]But when the sandstorm came, the trip became a disaster.
The drama unfolded during the May Day holiday. One girl did not make it before the students were rescued. The group was eventually found with the help of a GPS receiver. GPS, or global positioning system, is a satellite-based navigation system made up of a network of 24 satellites. It was originally created for military use by the US in 1980s but is now available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day. And the [34]service is free.
GPS satellites circle the earth twice a day and transmit signals and information to the earth. GPS receivers take this information and calculate the user's exact location. A GPS receiver must be locked on to the signals of at least three satellites to calculate the latitude and longitude of its location. With four or more satellites in view, the receiver can determine the user's altitude. [35]Once the user's position has been determined, the GPS receiver can calculate other information, such as speed, direction, distance to destination, and a whole lot more.

Questions 32 to 35 are based on the passage you have just heard.
32. What is true about the trip made by the young people?
正確答案：B
解析：錄音開頭提到：這三支探險(xiǎn)隊(duì)一開始的旅途非常愉快，但是，當(dāng)沙塵暴襲來(lái)時(shí)，沙漠之旅變成了一場(chǎng)災(zāi)難。故B正確。
33. What is the main topic of the passage?
正確答案：C
解析：主旨題應(yīng)該概括且含有核心詞，符合此要求的是C，全篇大部分文字都是在介紹GPS及其功用。
34. Which of the following is true about the GPS?
正確答案：D
解析：考查對(duì)細(xì)節(jié)的記憶，符合短文聽力“聽到什么選什么”的解題原則，答案為D。A錯(cuò)在scientific research，應(yīng)為military use；GPS在任何天氣情況下都一樣起作用，故B錯(cuò)；C中的指代有誤，主語(yǔ)若是A GPS receiver才與原文相符，故也排除C。
35. What must be determined first before the GPS receiver can calculate other information?
正確答案：A
根據(jù)錄音最后一句“一旦確定了使用者的位置，全球定位系統(tǒng)接收器就能計(jì)算其他的信息，如……”，可知A正確。