【正确答案】 C

【答案解析】[听力原文] 14-17
Although I think the U. S. generally has an excellent system of transporting people between cities that are only a few hundred miles apart, a person commuting between Detroit and Chicago, or between San Francisco and Los Angeles may spend only a relatively short time in the air while spending several hours getting to and from the airport. This situation makes flying almost as time- consuming as driving. Moreover, airplanes use a lot of their fuel just getting into the air. They simply are not fuel-efficient on short trips.
High-speed trains may be an answer. One fairly new proposal for such a train is for something called a "maglev", meaning a magnetically-levitated train.
Maglevs will not actually ride on the tracks, but will fly above tracks that are magnetically activated. This will save wear and tear on the tracks. These trains will be able to go faster than 150 miles per hour. At that speed, conventional trains have trouble staying on the tracks. As you can see, maglevs offer exciting possibilities for the future.
主旨题，问本文的中心议题。从全文看，说话者先提及相距较远城市之间用飞机作为交通工具的一些弊端，进而过渡到磁悬浮列车的各个方面，所以全文主要谈论的是一种新型的交通工具，故答案是C。

【正确答案】 A

【答案解析】细节题，问飞机在何种情况下最不省油。从They simply are not fuel-efficient on short trips可以直接看出答案是A。

【正确答案】 C

【答案解析】细节题，问磁悬浮列车的运行方式。从文中所说fly above tracks that are magnetically activated可以看出磁悬浮列车与普通列车的区别，故答案是C。

【正确答案】 B

【答案解析】推断题，问磁悬浮列车的优点之一。上题中提到的磁悬浮列车的运行方式直接会导致save wear and tear on the tracks，即轨道的维护需求就比普通铁轨要小一些，故答案是B。