单项选择题 A user calls about a problem with receiving email. After troubleshooting the user’s computer and finding nothing wrong, the technician contacts the email sender and finds out the user gave out their email address incorrectly. Which of the following is the BEST approach in explaining the issue to the user?（）

单项选择题 Which of the following features make using WPA2 versus WEP a BETTER choice in a wirelessenvironment?（）

多项选择题 Which of the following are advantages of using Dynamic Host Configuration Protocol?（）