----- Nội dung dịch tự động từ ảnh -----
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Read the passage carefully and choose the correct answer. (2p)
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It is estimated that over 99 percent of all species that ever existed have become extinct. What
causes extinction? When a species is no longer adapted to a change environment, it may die. The exact
causes of a species' death vary from situation to situation. Rapid ecological change may render an
environment hostile to
adapting. Food resources may
a species. For example, temperatures may change and a species may not 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.
analyses have also revealed that on some occasions many species became extinct at the same time-a
The fossil record reveals that extinction has occurred throughout the history of Earth. Recent
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 was 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 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
intersection of the earth's orbit with a cloud of comets, but this theory is purely speculative. Some
researchers have also speculated that extinction may often be random. That is, certain species may be
eliminated and others may survive for no particular reason. A species' survival may have nothing to do
with its ability or inability to adapt. If so, some of revolutionary history may reflect a sequence of
essentially random events.
1. The word "it" in line 2 refers to
A. environment
B. species
C. extinction
D. 99 percent
2. What does the author say in paragraph 1 regarding most species in Earth's history?
A. They have been able to adapt to ecological changes.
B. They have caused rapid change in the environment.
C. They have remained basically unchanged from their original forms
D. They are no longer in existence.
3. Which of the following is NOT mentioned in paragraph 1 as resulting from rapid ecological change?
A. Availability of food resources
B. Introduction of new species
C. Temperature changes D. Competition among species
4. The underlined word "ultimately" is closest in meaning to
B. unfortunately
A. finally
C. exceptionally
5. According to paragraph 2, evidence from fossils suggests that
A. There has been only one mass extinction in Earth's history.
D. dramatically
B. Extinction of species has occurred from time to time throughout Earth's history.
C. Extinctions on Earth have generally been massive.
D. Dinosaurs became extinct much earlier than scientists originally believed.
6. The word "demise" is closest in meaning to_
A. help
B. death
C. recovery
D. change
7. According to the passage, it is believed that the largest extinction of the species occurred
A. 65 million years ago
B. 250 million years ago
C. 225 million years ago
D. 26 million years ago