It’s suggested that the work ________ at once.

A. should do    B. must be done    C. be done    D. could do

阅读理解

阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项。

　　WASHINGTON - Considering the serious warnings lately about Internet viruses (病毒), users may be tempted (＝make sb. want to do sth. that especially is wrong) to unplug their machines just to keep them safe. In reality, common sense and a few basic tips can keep Internet surfers secure (＝safe).

　　Antivirus software is a must, and it should be updated (＝make sth. more modern or add new things to it) at least once a week to recognize newly released (释放的) viruses.

　　People with broadband Internet connections should also have 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 diskettes (软盘), the Internet brings viruses straight to the e-mail box. If an e-mail with attachment comes from an unknown sender, or unexpectedly from a known sender, it should not be opened.

　　On receipt (回执) of an unexpected attachment from a friend, experts suggest a telephone call to make sure of the mail's source before opening.

1．Why should antivirus software be updated at least once a week?

[　　]

A．Because the newly published antivirus software is more expensive.

B．Because the previous (先前的) antivirus software cannot work any longer.

C．Because the inventors of viruses have suggested this idea.

D．Because computer viruses are always developing.

2．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.

3．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 unplug our computers to defend ourselves from viruses.

D．Antivirus software made in some yeas ago is hard to protect today's computers.