What are two rules for compacting IPv6 addresses?（）

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