A.
(2, 4)-trees are equivalent to red-black trees (2,4)-树等价于红黑树
B.
Each internal node has no more than 4 branches 每个内部节点的分支数不超过4
C.
Each internal node has no less than 2 branches 每个内部节点的分支数不小于2
D.
Each node has exactly 3 keys except for the root 除了根节点外,每个内部节点都恰好包含3个关键码