A) They were killed off by an asteroid.

B) They died of drastic climate change.

C) They were wiped off by a volcanic eruption.

D) The cause of their extinction has remained a controversial issue.

5. What is the main thesis of the article?

A) Volcanic eruptions are not always deadly.

B) Older volcanic eruptions were more destructive.

C) Carbon dioxide emissions often give rise to global warming.
D) It is not easy to calculate the killing power of a volcanic eruption.

解标题：Older Volcanic（火山的） Eruptions（喷发）

本文讲的是远古火山喷发,所以older volcanic eruptions应是核心词。

1. Why did older volcanic eruptions do more damage than more recent ones?（为什么远古火山喷发比近期喷发损害更大？）

A. Because they killed off life more easily.

B. Because they were brighter.

C. Because they were larger.

D. Because they were hotter.

分析：细节题。第一题，一般在开头段落寻找答案。

Volcanoes were more destructive（更具有破坏性的）in ancient history（在古代的劳历史中）, not because （不是因为）they were bigger, but because （而是因为）the carbon dioxide（二氧化碳）they released（他们所释放的，定语修饰前面的the carbon dioxide） wipedout擦去、抹去 life生命 greater ease（更容易）.

句子是说：古代的火山更具杀伤力，不是因为它们更大，而是因为它们释放出来的二氧化碳更容易把人杀死。所以答案A表述的内容同本段相符。

2. How（如何，询问方式） did Wignall calculate （计算）the killing power （杀伤力）of those older volcanic eruptions?

A. By estimating how long they lasted.通过估计他们持续多长时间。

B. By counting the dinosaurs they killed.通过数死去的恐龙的的数量

C. By studying the chemical composition of lava.通过研究熔岩的化学构成。

D. By comparing the proportion of life wiped out with the volume of lava produced.通过比较火山释放出的熔岩的体积与杀死生命的比例。

分析：毫无疑问这是细节题，核心词就是人名：Wignall。

Paul Wignall（核心词出现了，接下来的内容请大家注意了！！！）from the University of Leeds was investigating the link between volcanic eruptions and mass extinctions. Not all volcanic eruptions killed off large numbers of animals, but all the mass extinctions over the past 300 million years coincided with huge formations of volcanic rock. To his surprise, the older the massive volcanic eruptions were, the more damage they seemed to do .  He（代指Wignall ） calculated the “killing efficiency（功效） for these volcanoes by comparing（比较）the proportion（比例）of life they killed off with the volume of lava（熔岩)that they produced. (答案出处！)He found that size for size, older eruptions were at least 10 times as effective at wiping out life as their more recent rivals.

3. When did dinosaurs become extinct?恐龙什么时候灭绝的？
A) 300 million years ago.

B) 250 million years ago.

C) 60 million years ago.

D) 65 million years ago

分析：这是标准的细节题，核心词：dinosaurs become extinct。而且这题的特点就是数字，所以在接下来的段落中大家要用笔标出所见到的数字加以判断！

The Permian extinction, for example, which happened 250 million years ago（答案B，但和dinosaurs become extinct没有关系，不是答案！）, is marked by floods of volcanic rock in Siberia that cover an area roughly the size of western Europe. Those volcanoes are thought to have pumped out about 10 gigatonnes of carbon as carbon dioxide. The global warming that followed wiped out 80 per cent of all marine genera at the time, and it took 5 million years for the planet to recover. Yet 60 million years ago（答案C，但和dinosaurs become extinct没有关系，不是答案！）, there was another huge amount of volcanic activity and global warming but no mass extinction. Some animals did disappear but things returned to normal within ten thousands of years. “The most recent ones hardly have an effect at all,” Wignall says. He ignored the extinction（该词是extinct的同根词，所以含义应是一样的！） which wiped out the dinosaurs(核心词露面了！) 65 million years ago（这是答案D，所以这就是我们