[单项选择]The nuclear polyhedrosis virus helps control gypsy moth populations by killing the moth’s larvae. The virus is always present in the larvae, but only every sixth or seventh year does the virus seriously decimate the number of larvae, thereby drastically setting back the gypsy moth population. Scientists believe that the virus, ordinarily latent, is triggered only when the larvae experience biological stress.
If the scientists mentioned above are correct, it can be inferred that the decimation of gypsy moth larvae populations by the nuclear polyhedrosis virus would be most likely to be triggered by which of the following conditions
A. A shift from drought conditions to normal precipitation in areas infested by gypsy moths.
B. The escalating stress of defoliation sustained by trees at tacked by gypsy moths for the second consecutive year.
C. Predation on larvae of all kinds by parasitic wasps and flies.
D. Starvation of the gypsy moth larvae as a result of overpopulation.
E. (E) Spraying of areas infested by gypsy moths with laboratory-raised nuclear polyhedrosis virus.

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Computer Virus and Virus Scan
A computer virus is a software program that attaches itself to another program in computer memory or on a disk, and spreads from one program to another. Viruses can damage data, cause computers to crash, display offending or bothersome messages, or lie dormant (保持静止的状态) until such time they are set to "awaken". In today’s industry, scanning is no longer considered to be an extravagance--but a necessity. Computer viruses no longer attack your computing environment only but all other computing environments which you contact. Computer viruses can attach themselves to the files being used and later propagate (复制) themselves through disks and files. Important information and hardware losses could plague (瘟疫，烦扰) your computing environment should you not take the proper precautions.
Many anti-virus products, such as Virus Scan, hold up the list of proper precautions. Scheduled periodic scans of your computing environme

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[单项选择]What measure has been taken to help Gypsy children
A. Special schools have been set up for them.
B. Permanent homes have been built for them.
C. They are now taught in their own language.
D. They are now allowed to attend local schools.

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[单项选择]A. It helps improve language fluency.
B. It helps improve one’s learning potential.
C. It is closely related to one’s interests.
D. It depends on individual experience.

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[单项选择]A. It helps to have a good sleep.
B. It helps to strengthen the bones.
C. It helps to supply enough blood to head.
D. It helps to exercise muscles in the body.

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