Melissa and LoveLetter made use of the l:rust that exists between friends or colleagues.Imagine receiving an (1)from a friend who asks you to open it.This is what happens with Melissa and several other similar email (2).Upon running, such worms usually proceed to send themselves out to email addresses from the victim's address book, previous emails, web pages (3). As administrators seek to block dangerous email attachments through the recognition of well-known (4),virus writers use other extensions to circumvent such protection.Executable (.exe) files are renamed to .bat and .cmd plus a whole list of other extensions and will still run and successfully infect target users. Frequently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the (5)access to your network.

空白（1）处应选择（）

A.attachment

B.packet

C.datagram

D.message

土壤有机质在改善土壤性质、调节土壤肥力上有（）作用？

A、土壤有机质可以提高土壤的供肥性

B、土壤有机质可以提高土壤的保肥性，因而可提高化肥利用率

C、土壤有机质可以改良土壤的多种物理性状

D、促进植物生长发育

E、有助于消除土壤污染，提高土壤自净能力