四六级考试

【单选题】The climate of earth has fluctuated quite a bit over the last 4.6 billion years of our planers history and it can be expected that the climate will continue to change. One of the most intriguing questions in earth science is whether the periods of ice ages are over or are we living in an "interglacial" period of time between ice ages
The geologic time period we are now living in is known as the Holocene(全新世). This epoch began about 11,000 years ago which was the end of the last glacial period and the end of the Pleistocene (更新世) epoch. The Pleistocene was an epoch of cool glacial and warmer interglacial periods which began about 1.8 million years ago.
Since the glacial period known as the "Wisconsin" in NorthAmerica and "Wrm" inEurope when over 10 million square miles (about 27 million km2) of NorthAmerica,Asia, andEurope were covered by ice, almost all of the ice sheets covering the land and glaciers in the mountains have retreateD、Today, about ten percent of the earth’s surface is covered by ice; 96% of this ice is located inAntarctica and GreenlanD、Glacial ice is also present in such diverse places asAlaska,Canada, New Zealand,Asia, andCaliforniA、
As only 11,000 years has passed since the last IceAge, scientists can not be certain that we are indeed living in a postglacial Holocene epoch instead of an interglacial period of the Pleistocene and thus due for another ice age in the geologic future. Some scientists believe that an increase in global temperature, as we are now experiencing, could be a sign of an impending ice age and could actually increase the amount of ice on the earth’s surface.
The cold, dry air above theArctic andAntarctica carries little moisture and drops little snow on the regions.An increase in global temperature could increase the amount of moisture in the air and increase the amount of snowfall.After years of more snowfall than melting, the Polar Regions could accumulate more ice.
An accumulation of ice would lead to a lowering of the level of the oceans and there would be further, unanticipated changes in the global climate system as well. Our short history on earth and our shorter record of the climate keeps us from fully understanding the implications of global warming. Without a doubt, an increase in the earth’s temperature will have major consequences for all life on this planet.
Which of the following is the best title for the passageA．Has the PleistoceneEpochEnded
B．Another IceAge in the Geologic Future IsComing
C．The IceAges:Are They Over
D．Glacial Ice WillBe Present inDifferent Places

网考网参考答案：C
网考网解析：
主旨题。文章先指出冰河时期是否结束还是个问题，接着指出有些科学家认为我们现在处于间冰期，并分析全球气候变暖可能使极地冰量增加，所以选C。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>