单选题

Transportation

For many years in the desert, camels used to be the only form of transportation (运输). Before the age of modern trains, camel trains were used to carry all the goods for trading between Central Africa and Europe. Traders sometimes put together camel trains with 10,000 to 15,000 animals. Each animal often carried as much as 400 pounds and could travel twenty miles a day. This form of transportation used to be so important that camels were called "ships of the desert".
Now modem trains travel across the desert in a very short time. One engine can pull as much weight as 135,000 camels. In addition, trains use special cars (车厢) for their load. Refrigerator cars carry food; boxcars (棚车) carry heavy goods; stock cars carry animals; and tank cars carry oil.
Air travel is also a modem means of transportation, but it has changed since the early 20th century. The earliest planes were biplanes (双翼飞机), with two sets of wings. The top speed of this plane was 60 miles per hour. The pilots used to sit or lie on the wings in the open air. The plane engines sometimes stopped in the middle of a trip. It used to be impossible to fly in bad weather. In snow or in rain, the wings frequently became icy. Then the plane might go down.
Mechanical improvements during the First World War changed airplanes. Monoplanes (单翼飞机) took the place of biplanes. Pilots flew inside of covered cabins. Still, even these planes were small and expensive. Only rich people used to be able to travel in airplanes.
Now modem jets make air travel possible for all people. No place in the world is more than 24 hours away by jet. Further improvements have lowered the cost of flying, and they have made air travel much safer than it used to be. A modern 707 can carry 170 people and can fly at 600 miles per hour. People never used to eat, sleep, or watch movies on airplanes. Now these things are a normal part of air travel.

单选题 According to the passage, why were camels called "ships of the desert"?

A、 Because they were strong and patient.
B、 Because they were the only important means of transportation in the desert.
C、 Because they moved faster than modern trains.
D、 Because they could travel 20 miles a day.

【正确答案】 B

【答案解析】[解析] 根据语境可知，第一段最后一句中的“This form of transportation”指的是骆驼(camels)。由此可知，骆驼之所以被称为“沙漠之舟”，是因为它们是沙漠中重要的交通工具。

单选题 Which of the following about the advantages of a train is NOT mentioned in Paragraph 2?

A、 Trains can use special cars for different purposes.
B、 Trains run much faster than camels.
C、 A train can carry much more goods than a camel.
D、 A train can carry goods at much lower costs.

【正确答案】 D

【答案解析】[解析] 根据第二段第一句可知，火车比骆驼速度快，故B被提到；根据第二段第二句可知，火车的载重远远大于骆驼，故C被提到；根据第二段最后两句可知，火车用专用车厢装不同货物，故A被提到。第二段并没提到火车的运货费用，故选D。

单选题 Biplanes were dangerous in bad weather because ______.

A、 pilots had to fly them at high speed.
B、 the wings were too soft for pilots to sit on.
C、 their engines were too hot to work.
D、 they might go down if the wings became icy.

【正确答案】 D

【答案解析】[解析] 根据第三段最后三句可知，双翼飞机在天气不好时飞行很危险，可能会因双翼结冰而坠落。故选D。

单选题 Which of the following led to the replacement of the biplane by the monoplane?

A、 Its large wings.
B、 Its small size.
C、 Its high price.
D、 The progress in science.

【正确答案】 D

【答案解析】[解析] 根据第四段前两句可知，机械改良是单翼飞机取代双翼飞机的原因。只有D项(科学进步)与这个原因最接近，故选D。

单选题 Which of the following would best replace the title of the passage?

A、 From Camels to Modern Jets.
B、 The Safest Means of Transportation.
C、 Camels—Ships of the Desert.
D、 The Role of Science in Transportation.

【正确答案】 A

【答案解析】[解析] 本文主要讲的是沙漠中交通工具的发展，所以A项(从骆驼到现代飞机)概括得最好。