总悬浮颗粒物
参考答案:
用标准大容量颗粒采样器在滤膜上所收集到的颗粒物的总质量,通常称为总悬浮颗粒物。用TSP表示。其粒径多在100m以下,尤以10m以下的为最多。
若命题p:(x-1)(x-3)≠0,q:x≠3,则p是q的( )
A.充分不必要条件
B.必要不充分条件
C.充要条件
D.既不充分也不必要条件
Melissa and LoveLetter made use of the trust that exists between friends orcolleagues.Imagine receiving an (71) from a friend who asks you to open it.This is whathappens with Melissa and several other similar email (72) .Upon running,such wormsusually proceed to send themselves out to email addresses from the victim’s address book,previous emails,web pages (73) .
A.memory B.caches C.ports D.registers
As administrators seek to block dangerous email attachments through the recognition ofwell—known (74) ,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 wilt still runand successfully infect target users.Frequently,hackers try to penetrate networks by sending an attachment thatlooks like a flash movie,which,while displaying some cute animation,simultaneouslyruns commands in the background to steal your passwords and give the (75) access to yournetwork.供选择答案: