[单项选择]

Passage One
Since the early 1980s, scientists have revealed some 40 human genes involved in cancer. These genes are essential for normal growth, but can be subverted to cause a tumor.
Dr. Jorge Yunis of the University of Minnesota Medical School in Minneapolis has found that 70 percent of oncogenes, or cancer-causing genes, are located near inherited weak points on chromosomes(染色体). Varying from individual to individual, vulnerable to chemical carcinogens(致癌剂), X rays and other cancer-inducing agents.
"If a chromosome snaps apart in the immediate vicinity of an oncogene," says Yunis, "normal genetic control mechanisms could break down and the stage would be set for the formation of cancer." Younis has shown that such a sequence occurs at the beginning of numerous leukemias (白血病), lymphomas(淋巴瘤) and some tumors of the lung, colon(结肠) and breast.
Yunis and other investigators have found that petroleum-based products--notabl
A. The lung.
B. The colon.
C. The chromosomes.
D. The breast.

[单项选择]

Passage One
Since the early 1980s, scientists have revealed some 40 human genes involved in cancer. These genes are essential for normal growth, but can be subverted to cause a tumor.
Dr. Jorge Yunis of the University of Minnesota Medical School in Minneapolis has found that 70 percent of oncogenes, or cancer-causing genes, are located near inherited weak points on chromosomes(染色体). Varying from individual to individual, vulnerable to chemical carcinogens(致癌剂), X rays and other cancer-inducing agents.
"If a chromosome snaps apart in the immediate vicinity of an oncogene," says Yunis, "normal genetic control mechanisms could break down and the stage would be set for the formation of cancer." Younis has shown that such a sequence occurs at the beginning of numerous leukemias (白血病), lymphomas(淋巴瘤) and some tumors of the lung, colon(结肠) and breast.
Yunis and other investigators have found that petroleum-based products--notabl
A. Scientific Findings.
B. Cancer-causing Genes.
C. Chromosome.
D. How Cancer Is Forme

[单项选择]Before the war ______ in the early 1980s, education provision in the south was inadequate.
A. erupted
B. blew
C. flared
D. burst

[单项选择]Since 1980s, home schooling ______.


A. has grown quickly with society accepting its educational philosophy
B. has decreased greatly with many children losing interest in studying at home
C. has faced the serious situation of losing social support
D. has adopted online teaching as its only approach

[单项选择]

Passage Five
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, Tambora threw 150 million ton of fine ash into the stratosphere. The ash from a volcano spreads worldwide in a few days and remains in the air for years. Its effect is to turn in coming solar radiation into space and thus cool the earth. For example, records of weather in Eng land show that between April and November 1815, the average temperature had fallen 4.5°F during the next twenty-four months, England suffered one of th
A. Weakened
B. Improved
C. Depreciated
D. Declined

[单项选择]The passage probably implies that scientists have been______.

[单项选择]According to the passage, scientists have positively confirmed that the brains of narcoleptics differ from those of normal brains in which of the following ways


A. Narcoleptic brains tend to remove degenerative tissue at a more prolific rate than that of nonnarcoleptics.
B. Narcoleptics are less responsive to drugs which treat neural autoimmune dysfunction than are nonnarcoleptics.
C. Nonnarcoleptics do not possess the same neurological immune antigens as narcoleptics.
D. Neurons that control muscle tone are damaged in the brains of narcoleptics, but not in those of non-narcoleptics.
E. (E) Narcoleptics experience greater neural degeneration as a result of aging than do nonnarcoleptics.

[单项选择]According to the passage, scientists are skeptical toward their equations because scientists ______.
A. work to explain real, rather than theoretical or simplified situations
B. know that well-defined problems are often the most difficult to solve
C. are unable to express their data in terms of multiple variables
D. are unwilling to relax the axioms they have developed

[单项选择]

Passage Four
Scientists have always wanted to know more about the other worlds in space. Years ago they knew a lot about the moon. They knew how big it is and how far away it is from the earth. But they wanted to know more about it. They thought and thought. At last they found the only way to know more was to send men to the moon.
The moon is about 384 000 kilometers away from the earth. A plane can not fly to the moon because the air reaches only 240 kilometers high above the earth. Then there is no air. But something can fly even when there is no air. That is’ a rocket (火箭).
Rockets can fly out into space. Rockets with men in them have already reached the moon. Some rockets without men in them have flown to other parts, much farther away from the earth than the moon in the universe. One day, rockets may be able to go to any place.

Which of the following is right（　）
A. So far, rockets with men have been to Other places.
B. Rockets with men can fly to other places farther away than the moon.
C. Perhaps one day rockets will be able to go to any place in space.
D. A plane can fly to the moon.