托福阅读真题+题目+答案：Determining Past Climates

托福阅读真题+题目+答案：Determining Past Climates

Glaciers form over land where temperatures are sufficiently low so that, during the course of a year, more snow falls than melts. Successive snow accumulations over many years compact the snow, which slowly recrystallizes into ice. Under the influence of gravity, the ice begins to move, and a glacier is form. A mere 18,000 years ago, Earth was in the grip of a cold spell, with alpine glaciers extending down river valleys and continental glaciers covering vast areas of North America and Europe. The ice measured several kilometers thick and extended as far south as New York and the Ohio River Valley. Perhaps glaciers advanced ten times during the past two million years, only to retreat. In the warmer periods between glacier advances, average global temperatures were slightly higher than they are at present.

In mentioning temperatures that are “sufficiently” low, the author means temperatures that are

A.extremely low

B.low enough

C.low at times

D.always low

According to paragraph 1, which of the following does NOT correctly characterize glaciers?

A.They form over land.

B.They result when snow repeatedly melts and refreezes.

C.They move.

D.They accumulate snow over many years.

The word “compact” in the passage is closest in meaning to

A.place under a heavy weight

B.press together

C.increase

D.transform

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

A.Just 18,000 years ago, glaciers covered large areas of North America and Europe.

B.A mere 18,000 years ago, vast areas of North America and Europe were in the grip of a cold spell.

C.Alpine glaciers once expanded outward from river valleys to cover most of continental Europe and North America.

D.During serious cold spells, glaciers covered not only alpine river valleys, but large portions of whole continents.

The geological evidence left behind by advancing and retreating is one factor suggesting that global climate has undergone slow but continuous changes. To reconstruct past climates, scientists must examine and then carefully piece together all the available evidence. Unfortunately, the evidence only gives a general understanding of what the climate was like. For example, fossil pollen of a tundra plant collected in a layer of sediment in New England and dated to be 12,000 years old suggests that the climate of that region used to be much colder.

The word “undergone” in the passage is closest in meaning to

A.arisen from

B.led to a decrease in

C.experienced

D.contributed to

。。。。。。余下托福阅读真题原文及题目省略！

托福阅读真题+题目+答案：Determining Past Climates，完整版下载，10元有偿！