单项选择题
	A. Login using a different account
	B. Install an Internet firewall
	C. Install an email spam filter
	D. Go back to a previous restore point
单项选择题 A floppy drive is replaced in a computer and now when the computer is turned on the floppy drive light is constantly lit. Which of the following is the MOST likely cause?()
单项选择题 A mirrored set is another name for which of the following?()
单项选择题 A laser printer keeps printing out crumpled pages from the third tray. Which of the following is the MOST likely explanation?()