TOEFL READING PRACTICE WITH ANSWERS
TOEFL 3 (READING PASSAGE 5)
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Questions
45-50
Volcanic
fire and glacial ice are natural enemies. Eruptions at glaciated volcanoes
typically destroy ice fields as they did in 1980 when 70 percent of Mount
Saint Helens ice cover was demolished. During long dormant intervals,
glaciers gain the upper hand cutting deeply into volcanic cones and
eventually reducing them to rubble. Only rarely do these competing forces
of heat and cold operate in perfect balance to create a phenomenon such as
the steam caves at Mount Rainier National Park.
Located
inside Rainier's two ice-filled summit craters, these caves form a
labyrinth of tunnels and vaulted chambers about one and one -half miles in
total length. Their creation depends on an unusual combination of factors that
nature almost never brings together in one place. The cavemaking recipe
calls for a steady emission of volcanic gas and heat, a heavy annual
snowfall at an elevation high enough to keep it from melting during the
summer, and a bowl-shaped crater to hold the snow.
Snow
accumulating yearly in Rainier's summit craters is compacted and compressed
into a dense form of ice called firm, a substance midway between ordinary
ice and the denser crystalline ice that makes up glaciers. Heat rising from
numerous openings (called fumaroles) along the inner crater walls melts out
chambers between the rocky walls and the overlying ice pack. Circulating currents
of warm air then melt additional openings in the firm ice, eventually
connecting the individual chambers and, in the large of Rainier's two
craters, forming a continuous passageway that extends two-thirds of the way
around the crater's interior.
To
maintain the cave system, the elements of fire under ice must remain in
equilibrium enough snow must fill the crater each year to replace that
melted from below. If too much volcanic heat is discharged, the crater's
ice pack will melt away entirely and the caves will vanish along with the
snows of yesteryear. If too little heat is produced, the ice, replenished
annually by winter snowstorms will expand, pushing against the enclosing
crater walls and smothering the present caverns in solid firm ice.
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45.With
what topic is the passage primarily concerned?
(A)
The importance of snowfall for Mount Rainier
(B)
The steam caves of Mount Rainer
(C)
How ice covers are destroyed
(D)
The eruption of Mount Saint Helens in 1980
46.The
word " they" in line 2 refers to
(A)
fields
(B)
intervals
(C)
eruptions
(D)
enemies
46.
According to the passage long periods of volcanic inactivity can lead to a
volcanic cone's
(A)
strongest eruption
(B)
sudden growth
(C)
destruction
(D)
unpredictability
47.
The second paragraph mentions all of the following as necessary clements in
the creation of stream caves EXCEPT
(A)
a glacier
(B)
a crater
(C)
heat
(D)
snow
48.
According to the passage, heat from Mounts Rainer's summit craters rises from.
(A)
crystalline ice
(B)
firms
(C)
chambers
(D)
fumaroles
49.
In line 26 "smothering" the caverns means that they would be
(A)
eliminated
(B)
enlarged
(C)
prevented
(D)
hollowed
50.
According to the passage, heat from Mount Rainier's summit craters rises
from
(A)
crystalline ice
(B)
firns
(C)
chambers
(D)
fumaroles
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ANSWER KEY
45. B
46. C
47. C
48. A
49. D
50. A
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