Passage 1
Scientists claim that air pollution causes a decline in the world‘s average air temperature. In order to prove that theory, ecologists have turned to historical data in relation to especially huge volcanic eruptions. They suspect that volcanoes effect weather changes that are similar to air pollution.
One source of information is the effect of the eruption of Tambora, a volcano in Sumbawa, the Dutch East Indies (the former name of the Republic of Indonesia), in April 1815. The largest recorded volcanic eruption of Tambora threw 150 million tons of fine ash into the stratosphere. The ash from the volcano spreads worldwide in a few days and remains in the air for years. Its effect is to turn incoming solar radiation into space and thus cool the earth. For example, records of weather in England show that between April and November 1815, the average temperature had fallen 4.5℉. During the next twenty-four months, England suffered one of the coldest periods of its history. Farmers‘ records from April 1815 to December 1818 indicate frost throughout the spring and summer and sharp decreases in crop and livestock markets. Since there was a time lag of several years between cause and effect, by the time the world agricultural commodity community had deteriorated, no one realized the cause.
Ecologists today warn that we face a twofold menace. The ever-present possibility of volcanic eruptions, such as that of Mt. St. Helens in Washington, added to man‘s pollution of the atmosphere with oil, gas, coal, and other polluting substances, may bring us increasingly colder weather.
According to the passage, the effects of Tambora‘s eruption were _____.
细节题。 根据文章第二段第四、 五句"Its effect is to turn incoming solar radiation into space and thus cool the earth."可知， 火山爆发后产生的灰尘使地球气温下降， 故选C项。
Which of the following was the cause of cold weather in England from 1815 to 1818?
推理题。 由上文可知， 英国1815年到1818年气温下降是作者用来证实火山爆发后火山灰留在大气层从而造成地球表面气温下降所举的事例。 故选B项。
No one realized the cause of the deterioration of the world agricultural commodity market because _____.
细节题。 根据文章第二段最后一句"Since there was a time lag of several years between cause and effect, by the time the world agricultural commodity community had deteriorated, no one realized the cause."可知， 没有人意识到世界农产品市场恶化的原因是因果效应的时间间隔较长， 故选A项。
According to the passage, which of the following is NOT the cause of dropping temperature?
推理题。 由文章可知， 气温下降会导致种植业和畜牧业产量的缩减， 所以C选项是气温下降的结果， 而并非原因。 故选C项。
The ―twofold menace‖ in the last paragraph refers to _____.
细节题。 根据文章最后一段可知， 人类目前所面临的双重威胁在于大气污染和气温下降。 文中提到"volcanic eruption...added to man‘s pollution of the atmosphere"， 也就是说随时可能爆发的火山和人类燃烧石油、 天然气等造成大气污染， 而且可能进一步导致气温持续下降。 火山的爆发只是作为大气污染的其中一部分。 故选C项。