Question

    In the 1960s, while studying the volcanic history of Yellowstone National Park, Bob Christiansen became puzzled about something that, oddly, had not troubled anyone before: he couldn’t find the park’s volcano. It had been known for a long time that Yellowstone was volcanic in nature — that’s what accounted for all its hot springs and other steamy features. But Christiansen couldn’t find the Yellowstone volcano anywhere.

Most of us, when we talk about volcanoes, think of the classic cone(圆锥体) shapes of a Fuji or Kilimanjaro, which are created when erupting magma(岩浆) piles up. These can form remarkably quickly. In 1943, a Mexican farmer was surprised to see smoke rising from a small part of his land. In one week he was the confused owner of a cone five hundred feet high. Within two years it had topped out at almost fourteen hundred feet and was more than half a mile across. Altogether there are some ten thousand of these volcanoes on Earth, all but a few hundred of them extinct. There is, however, a second less known type of volcano that doesn’t involve mountain building. These are volcanoes so explosive that they burst open in a single big crack, leaving behind a vast hole, the caldera. Yellowstone obviously was of this second type, but Christiansen couldn’t find the caldera anywhere.

Just at this time NASA decided to test some new high-altitude cameras by taking photographs of Yellowstone. A thoughtful official passed on some of the copies to the park authorities on the assumption that they might make a nice blow-up for one of the visitors’ centers. As soon as Christiansen saw the photos, he realized why he had failed to spot the caldera: almost the whole park—2.2 million acres—was caldera. The explosion had left a hole more than forty miles across—much too huge to be seen from anywhere at ground level. At some time in the past Yellowstone must have blown up with a violence far beyond the scale of anything known to humans.

1.What puzzled Christiansen when he was studying Yellowstone?

A.Its complicated geographical features.

B.Its ever-lasting influence on tourism.

C.The mysterious history of the park.

D.The exact location of the volcano.

2.What does the second paragraph mainly talk about?

A.The shapes of volcanoes.

B.The impacts of volcanoes.

C.The activities of volcanoes.

D.The heights of volcanoes.

3.What does the underlined word “blow-up” in the last paragraph most probably mean?

A.Hot-air balloon. B.Digital camera.

C.Big photograph. D.Bird’s view.

Answer

1.D

2.A

3.C

【解析】

这是一篇说明文。文章讲述了二十世纪六十年代Bob Christiansen在研究黄石公园的火山历史时，奇怪地发现到处看不到火山的影子，原来，这儿的火山并不是像我们大部分人想象的那种圆锥体形状的高耸的样子，而是一个巨大的洞，这个洞太大了以至于从地面上的任何地方都看不见。

1.细节理解题。根据第一段最后一句But Christiansen couldn’t find the Yellowstone volcano anywhere.可知，他困惑的是在黄石公园找不到火山。故选D。

2.主旨大意题。本段讲述了两种形状的火山，一种是通常人们所理解的由火山岩浆堆积形成的圆锥体，还有一种极具爆发力的火山，它们会在一个大裂缝中爆裂，留下一个巨大的洞，故选A。

3.词义猜测题。根据第三段第一句Just at this time NASA decided to test some new high-altitude cameras by taking photographs of Yellowstone. A thoughtful official passed on some of the copies to the park authorities on the assumption that they might make a nice blow-up for one of the visitors’ centers.可知，美国国家航空航天局为测试一些新的高海拔照相机而拍摄了黄石公园的照片。一位深思熟虑的官员把其中的一些照片副本转交给了公园管理部门，认为他们可能会将其放大以供一个游客中心展示。根据常识可知，游客中心的照片一般都很大，以吸引游客的注意，故此处意为“将照片放大”，选C。