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托福聽力真題CH系列 005套

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extinction of large North American mammals
第1題
What is the main purpose
of the lecture?
A To illustrate similarities between two periods of
climate change
B To examine theories about the extinction of large North
American mammals
C To describe how scientists verify occurrences of
meteor impacts on Earth
D To present a new explanation for the cause of
the end of the last ice age

第2題
What is the professor’s opinion of the
claim that cooling during the Younger Dryas caused a major extinction?
A
It will probably be proven correc t by future research
B It has been
strongly contradicted by recent soil-sample analysis
C It seems unlikely
in view of what is known about similar climate changes
D It is based on a
misinterpretation of evidence collected in North Americans

第3題
Why does
the professor mention a meteor that struck Earth during the time of the
dinosaurs?
A To imply that that meteor impact also affects other large
animals in North America
B To point out that Earth was often struck by
meteors in the past
C To explain why scientists hypothesize that a
similar impact could have caused a later extinction event
D To challenge
a commonly accepted claim about dinosaur extinction

第4題
According to the
professor, what is the major significance of the Younger Dryas
Boundary?
A It provides proof of a sudden climate change.
B It lines the
inside of a 13,000-year-old impact crater.
C It contains valuable
information on about the composition of meteors.
D It marks the
disappearance of large mammal species.

第5題
The professor mentions that a
new group of researchers collected samples from a Younger Dryas Boundary
site. How did those researchers explain the high concentration of
magnetic particles in the samples?
A The Younger Dryas Boundary is
especially thick at that site.
B The particles were carried to the site
by flowing water.
C A meteor caused a high concentration of the particles
at the site.
D Old roofing material had been buried at the site.

第6題
What
opinion does the professor express when he discusses nanodiamonds?
A
Their presence is not strong proof of a meteor impact
B They indicate
that a geological sample has been contaminated
C Researchers should get a
better understanding of their origin
D Researchers should focus on
magnetic particles instead of nanodiamonds

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