What are two rules for compacting IPv6 addresses？（）

• A、The maximum number of times a double colon can replace a 16-bit segment that consists of all zeroes is two
• B、The leading zeroes in any 16-bit segment do not have to be written.
• C、Every 16-bit segment that consists of all zeroes can be represented with a single colon
• D、The trailing zeroes in any 16-bit segment do not have to be written.
• E、Any single， continuous string of one or more 16-bit segments that consists of all zeroes can be represented with a double colon
• F、Two zeroes in the middle of any 16-bit segment do not have to be written