问题详情

C
WASHINGTON - considering the serious warnings lately about Internet viruses(病毒) , users may don " t use their machines just to keep them safe. In reality , common sense and a few basic tips can keep Internet surfers secure.
Anti-virus software is a must, and it should be updated at least once a week to recognize newIy viruses. If this is not done, you will meet great troubles.
People with broadband Internet connections should have also a frrewall. These protect the computer from attacks by hackers(黑客) .
Then it is time to think about computer habits. Unlike old viruses, which spread only through shared disks, the Intemet brings viruses straight to the e-mail box. If an e-mail with attachment(附件) comes from an unknown sender, or unexpectedly from a known sender, it should not be opened.
On receiving an unexpected attachment from a friend, experts suggest a telephone call to make sure of the mail" s source before opening. If you open the mail without any consideration, you will be easily attacked by the hackers.
65. Why should anti-virus software be updated at least once a week？
[ A] Because the newly published anti-virus software is more expensive.
[ B ] Because the previous(先前的 ) anti-virus software cannot work any longer.
[C]Because the inventors of viruses have suggested this idea.
[ D ] Because computer viruses are always developing.请帮忙给出正确答案和分析，谢谢！