41.Older volcanic eruptions did moredamage than more recent ones because

A. older volcanoes were brighter.

B. carbon dioxide made the earth muchwarmer

C. older volcanoes were hotter

D. carbon dioxide killed off life moreeasily

答案：d

42. Wignall calculated the killing powerof those older volcanic eruptionsby

A. estimating how long they lasted

B. counting the dinosaurs they killed

C. comparing the proportion of lifekilled with the volume of lavaproduced

D. studying the chemical composition oflava

答案：c

43. When did dinosaurs become extinct?

A. 300 million years ago.

B. 250 million years ago

C. 65 million years ago

D. 60 million years ago

答案：c

44. It can be inferred from Paragraph 3that the cause of dinosaur extinctionis_______

A. a political issue.

B. self-evident.

C. quite certain

D. controversial

答案：d

45. What is the main thesis of thearticle?

A. Volcanic eruptions are not alwaysdeadly.

B. Carbon dioxide emissions often giverise to global warming.

C. Older volcanic eruptions are moredestructive

D. It is not easy to calculate the killingpower of a volcanic eruption

答案：c