恐龙是怎样灭绝的 英文表达

题目

恐龙是怎样灭绝的 英文表达

答案

How did the dinosaurs become extinct?This is a question that has stumped scientists ever since dinosaur fossils were first discovered.There are many theories as to how the dinosaurs became extinct.This page presents some of the most popular thoeries.Keep in mind that there is no absolutely proven theory.Noone knows for certain exactly why and how the dinosaurs became extinct.
Probably the most popular theory right now is the Asteroid Theory.According to this theory a large asteroid or comet collided with Earth about 65 million years ago.Scientists think that such a large collision would throw so much dust into the air that sunlight would not be able to shine and plants and animals would die.The dramatic changes in climate that resulted from this huge collision were too much for the dinosaurs.They were not able to survive.
Another theory that could explain how the dinosaurs became extinct is volcanic activity.A huge increase in volcanic activity at around 65 millions years ago could have pumped so much ash into the air that it blocked out the sun killing the dinosaurs.
Some scientists believe that there was a severe ice age.Throughout Earth's history there have been many ice ages.The last one ended about 10,000 years ago.A very severe ice age could have changed temperatures and frozen a lot of Earth's water.The dinosaurs would not be able live under such conditions and that is how the dinosaurs became extinct.
It has also been suggested that desease killed off the dinosaurs.A very deadly and contagious desease may have circulated among the dinosaurs forcing them to become extinct.
Still yet another theory is that the Earth just gradually changed in climate over a long time period and the dinosaurs were not able to adapt to the cooler,dryer climate.
There are probably other theories as to how the dinosaurs became extinct.One thing is for certain.All dinosaurs that we know of are extinct.How did all the dinosaurs become extinct?Maybe one of these theories is the right answer.However,it is difficult to explain why all the dinosaurs died out but many other animals survived.Perhaps one day we will know for certain how the dinosaurs became extinct.Until then we must speculate and continue the search for the answer to this great mystery of nature.