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1996年10月托福阅读全真试题(1) |
| 来源:www.stu88.com 时间:2006-04-27 |
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Question 1-8
When Jules Verne wrote Journey to the Center of the
Earth in 1864, there were many conflicting theories about the
nature of the Earth’s interior. Some geologists thought that it
contained a highly compressed ball of incandescent gas, while
others suspected that it consisted of separate shells, each made
of a different material. Today, well over a century later, there
is still little direct evidence of what lies beneath our feet. Most
of our knowledge of the Earth’s interior comes not from mines
or boreholes, but from the study of seismic waves - powerful
pulses of energy released by earthquakes.
The way that seismic waves travel shows that the Earth’s
interior is far from uniform. The continents and the seabed
are formed by the crust - a thin sphere of relatively light, solid
rock. Beneath the crust lies the mantle, a very different layer
that extends approximately halfway to the Earth’s center.
There the rock is the subject of a battle between increasing
heat and growing pressure.
In its high levels, the mantle is relatively cool; At greater
depths, high temperatures make the rock behave more like a
liquid than a solid. Deeper still, the pressure is even more
intense, preventing the rock from melting in spite of a
higher temperature.
Beyond a depth of around 2,900 kilometers, a great
change takes place and the mantle gives way to the core. Some
seismic waves cannot pass through the core and others are bent
by it. From this and other evidence, geologists conclude that
the outer core is probably liquid, with a solid center. It is
almost certainly made of iron, mixed with smaller amounts
of other elements such as nickel.
The conditions in the Earth’s core make it a far more
alien world than space. Its solid iron heart is subjected to
unimaginable pressure and has a temperature of about 9,000oF.
Although scientists can speculate about its nature, neither
humans nor machines will ever be able to visit it.
1. The word "conflicting" in line 2 is closest in meaning to
(A) controlling
(B) outdated
(C) opposing
(D) important
2. What is today’s richest source of information about the Earth’s interior for geologists?
(A) Boreholes
(B) Shells
(C) Seismic waves
(D) Mines
3. The word "There" in line 16 refers to the
(A) mantle
(B) crust
(C) seabed
(D) Earth’s center.
4. Which of the following is a primary characteristic of the Earth’s mantle?
(A) Light, solid rock
(B) Uniformity of composition
(C) Dramatically increasing pressure
(D) Compressed, incandescent gas
5. The phrase "gives way to" in line 24 is closest in meaning to
(A) runs along
(B) rubs against
(C) turns into
(D) floats on 共7页: 1 [2] [3] [4] [5] [6] [7] 
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