THE WRITER OF THIS PASSAGE IS ATTEMPTING TO ______.A. EXPLAIN HOW...

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70. The writer of this passage is attempting to ______.

A. explain how reading habits have developed

B.

C. show how reading methods have improved

D. encourage the growth of reading

Passage 2:

It is estimated that over 99 percent of all species that ever existed have become extinct. What

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causes extinction? When a species is no longer adapted to a change environment, it may perish. The

environment hostile to a species. For example, temperatures may change and a species may not be adapt.

Food resources may be affected by environmental changes, which will then cause problems for a species

requiring these resources. Other species may become better adapted to an environment, resulting in

competition and,

ultimately,

in the death of a species.

The fossil record reveals that extinction has occurred throughout the history of Earth. Recent

analyses have also revealed that on some occasions many species became extinct at the same time - a

mass extinction. One of the best - known examples of mass extinction occurred 65 million years ago

with the

demise

of dinosaurs and many other forms of life. Perhaps the largest mass extinction was the

one that occurred 225 million years ago, when approximately 95 percent of all species died. Mass

extinctions can be caused by a relatively rapid change in the environment and can be worsened by the

close interrelationship of many species. If, for example, something were to happen to destroy much of

the

plankton

in the oceans, then the oxygen content of Earth would drop, affection even organisms not

living in the oceans. Such a change would probably lead to a mass extinction.

One interesting, and controversial,

finding

is that extinctions during the past 250 million years

have tended to be more intense every 26 million years. The periodic extinction might be due to

researchers have also speculated that extinction may often be random. That is, certain species may be

with its ability or inability to adapt. If so, some of revolutionary history may reflect a sequence of

essentially random events.