Which two wireless security statements are true？（）

• A、A TACACS+ server is required to implement 802.1x.
• B、MIC protects against man-in-the-middle and replay attacks.
• C、The 802.1x standard provides encryption services for wireless clients.
• D、The AES （symmetric block cipher） is specified in the IEEE 802.11i specification.
• E、The IEEE 802.11i specification uses RC4 as its encryption mechanism.
• F、WPA requires TKIP and AES as encryption methods.