1996年5月托福阅读全真试题
33.What is the passage mainly about？
（A） Streamboat engines in the western United States
（B） River travel in the western United States
（C） A famous United States inventor
（D） The world's first practical streamboat
34.What was the Clermont （line14）？
（A） A river
（B） A factory
（C） A boat
（D） an engine
35.Who developed the kind of stream engine used on western streamboats？
（A） Watt
（B） Boulton
（C） Fulton
（D） Evans
36.The word "novel" in line 18 is closest in meaning to
（A） fictional
（B） intricate
（C） innovative
（D） powerful
37.What option of Evans is suggested by the use of the term "unsung hero" in line 18？
（A） More people should recognize the importance of his work.
（B） More of his inventions should be used today.
（C） He should be credited with inventing the stream engine.
（D） More should be learned about his early life.
38.What does the author imply about Evans？
（A） He went to England to learn about stream power.
（B） He worked for Fulton.
（C） He traveled extensively in the West.
（D） He taught himself about stream engines.
39.The word "stationary" in line 23 is closest in meaning to
（A） single
（B） fixed
（C） locomotoiv
（D） modified
40.The word "they" in line 25 refers to
（A） engines
（B） mechanized production and steam power
（C） possibilities
（D） steamboats
41.What does the author imply about the western rivers？
（A） It was difficult to find fuel near them.
（B） They flooded frequently.
（C） They were difficult to navigate.
（D） They were rarely used for transportation.
42.The word "it" in line 31 refers to
（A） decade
（B） high-pressure engine
（C） weight
（D） problem
43.The word "vessel" in line 33 is closest in meaning to
（A） fuel
（B） crew
（C） cargo
（D） craft
44.Which of the following points was made by the critics of high-pressure engines？
（A） They are expensive to import.
（B） They are not powerful enough for western waters.
（C） They are dangerous.
（D） They weigh too much.
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 cave-making 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 firn，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 opening in the firn ice， eventually connecting the individual chambers and， in the larger 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 snow 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 firn ice.