2015年9月12日托福阅读真题+题目+答案：Gliding and Soaring

2015年9月12日托福阅读真题+题目+答案：Gliding and Soaring 

1. Gliding is gravity-powered flight where the movement of the glider has a downward tilt. But many birds are capable of ascending without flapping their wings, and this is called soaring.Birds usually soar by finding air that is rising as fast as or faster than the gliding bird's sinking speed. For example, a turkey vulture might glide with a sinking speed of about 0.8 meters per second. If the vulture can find a place where the air is rising at 0.8 meters per second, it will be able to maintain a constant altitude. If it finds air rising faster than that, it will be able to climb.

2. Two common processes produce updrafts, or rising air. When heated air rises, it is called a thermal, and when wind blows up a hill or over a large obstacle, it is called ridge lift or slope lift. Thermals occur when the Sun heats some parts of the ground more than others. For example, a freshly plowed field may heat up faster than an adjacent meadow. The warm ground heats the air above it, and the air starts to rise. As the warm air rises, it is replaced by cool air from the surrounding terrain, and this new air is heated until it rises. Thermals may be continuous chimneys of rising air, or a series of discrete, doughnut-shaped bubbles (ring thermals) formed at intervals by the warmed ground.

3. If they could be made visible, ring thermals would look like giant, rising smoke rings. Some airplane pilots and biologists disagree about the exact form of continuous thermal chimneys. Pilots have traditionally interpreted thermals as large, tall columns of rising air, usually with a cumulus (white, fluffy) cloud marking the top of the column. In contrast, observers of animal flight find only small, localized thermal chimneys, which usually take the form of dust devils, which are small columnar thermals with intense rotation. Colin Pennycuick, a prolific researcher on bird flight, discounts thermal chimneys and recognizes only ring thermals as sources of large-scale, long-lasting updrafts. In any case, thermals can rise 2 or 3 kilometers above the ground. Also, they tend to increase in size and intensity as they rise, sometimes reaching over 1,000 meters in diameter. Thermals are usually capped by a cloud, because the upper limit of a thermal is set by the altitude where the temperature is low enough to condense water vapor in the thermal, which cools the air and forms a cloud.

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托福阅读真题题目：

1..Which of the following plays a role in helping a bird to soar

A. Gravity

B. Wing flapping

C. Gliding

D. Rising air

2..In paragraph 1, why does the author discuss the example of a turkey vulture in flight

A. To explain why birds sink unless they find currents of rising air

B. To provide information about sinking and soaring speeds typical for large birds

C. To illustrate why gliding birds seek out rapidly rising air currents

D. To clarify the relationship between sinking speed and the speed of rising air needed to soar

3..The word adjacent in the passage is closest in meaning to

A. open

B. nearby

C. densely covered

D. sunny

4..The phrase at intervals in the passage is closest in meaning to

A. at low elevations

B. in areas without vegetation

C. periodically

D. unevenly

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2015年9月12日托福阅读真题+题目+答案：Gliding and Soaring ，完整版下载，10元有偿！