患儿7岁，左下第一恒磨牙在龋洞去腐过程中意外穿髓，应选的治疗方法为（）

A.根管治疗

B.活髓切断术

C.干髓术

D.根尖诱导成形

E.塑化治疗

Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagine receiving an (71) from a friend who asks you to open it. This is what happens with Melissa and several other similar email (72) . Upon running, such worms usually proceed to send themselves out to email addresses from the victim’s address book, previous emails, web pages (73) .
As administrators seek to block dangerous email attachments through the recognition of well-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 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 (75) access to your network.

A．cracker

B．user

C．customer

D．client