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Q40: In response to viral infection, the immune systems of mice typically produce antibodies that destroy the virus by binding to proteins on its surface. Mice infected with a herpesvirus generally develop keratitis, a degenerative disease affecting part of the eye. Since proteins on the surface of cells in this part of the eye closely resemble those on the herpesvirus surface, scientists hypothesize that these cases of keratitis are caused by antibodies to herpesvirus.
Which of the following, if true, gives the greatest additional support to the scientists’ hypothesis?
- Other types of virus have surface proteins that closely resemble proteins found in various organs of mice.
- There are mice that are unable to form antibodies in response to herpes infections, and these mice contract herpes at roughly the same rate as other mice.
- Mice that are infected with a herpesvirus but do not develop keratitis produce as many antibodies as infected mice that do develop keratitis.
- There are mice that are unable to form antibodies in response to herpes infections, and these mice survive these infections without ever developing keratitis.
- Mice that have never been infected with a herpesvirus can sometimes develop keratitis.
Answer: A(D) Q40(看不懂?????): Parland’s alligator population has been declining in recent years, primarily because of hunting. Alligators prey heavily on a species of freshwater fish that is highly valued as food by Parlanders, who had hoped that the decline in the alligator population would lead to an increase in the numbers of these fish available for human consumption. Yet the population of this fish species has also declined, even though the annual number caught for human consumption has not increased.
Which of the following, if true, most helps to explain the decline in the population of the fish species?
- The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous.
- Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use.
- Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population.
- During Parland’s dry season, holes dug by alligators remain filled with water long enough to provide a safe place for the eggs of this fish species to hatch.
- In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting.
Answer: B(D) Q30: Editorial:
In Ledland, unemployed adults receive government assistance. To reduce unemployment, the government proposes to supplement the income of those who accept jobs that pay less than government assistance, thus enabling employers to hire workers cheaply. However, the supplement will not raise any worker’s income above what government assistance would provide if he or she were not gainfully employed. Therefore, unemployed people will have no financial incentive to accept jobs that would entitle them to the supplement.
Which of the following, if true about Ledland, most seriously weakens the argument of the editorial?
- The government collects no taxes on assistance it provides to unemployed individuals and their families.
- Neighboring countries with laws that mandate the minimum wage an employer must pay an employee have higher unemployment rates than Ledland currently has.
- People who are employed and look for a new job tend to get higher-paying jobs than job seekers who are unemployed.
- The yearly amount unemployed people receive from government assistance is less than the yearly income that the government defines as the poverty level.
- People sometimes accept jobs that pay relatively little simply because they enjoy the work.
Answer: C | 
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发表于 2007-9-30 22:56:00
