单选题 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-vires software is a must, and it should be updated at least once a week to recognize newly viruses. If this is not done, you will meet great troubles.
People with broadband Internet connections should have also a firewall, 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 Internet 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.

单选题 Why should anti-vires software be updated at least once a week?

A、 Because the newly published anti-vires software is more expensive.
B、 Because the previous (先前的) anti-vires software cannot work any longer.
C、 Because the inventors of viruses have suggested this idea.
D、 Because computer viruses are always developing.

【正确答案】 D

【答案解析】[解析] 事实细节题。从文章第二段第一句话，Anti-vires software is a must，and it should be updated at least once a week to recognize newly viruses．我们可以看出，新的计算机病毒总是在不断地出现、不断地升级换代。以前的防毒软件可能不行了。所以正确的答案为D。

单选题 Which of the following is suggested by computer experts?

A、 Don't rush to open any e-mail attachment.
B、 Never open any e-mail attachment.
C、 It's always safe to open an e-mail attachment from a friend.
D、 Whenever you receive an e-mail, you should make a call to make sure whom it comes from.

【正确答案】 A

【答案解析】[解析] 判断推理题。从第四自然段最后一句If an e-mail with at- tachment(附件)comes from an unknown sender，or unexpectedly from a known sender，it should not be opened．可知，不可以盲目地打开邮件的附件。所以正确的答案为A。

单选题 Which of the following is NOT right according to the passage?

A、 Something can be done to keep our computers safe.
B、 Even an e-mail attachment coming from a friend may not be safe to open.
C、 We should not use our computers to defend ourselves from viruses.
D、 Anti-virus software made some years ago is hard to protect today's computers.

【正确答案】 C

【答案解析】[解析] 判断推理题。选项A、B、D的内容在文章中均有体现，可是选项C是荒谬、错误的。我们按照基本的常识就可以将它排除。计算机不能因为有感染病毒的可能，就关机不再用了。所以正确的答案为C。