下列关于二叉树性质的说法正确的有：（多选） Which sentences of the followings are right about a binary tree's characterization:（There are more than one correct answers）

A、非空满二叉树的结点个数一定为奇数个。 The amount of nodes of a full binary tree with at least one node must be odd.

B、非完全二叉树也可以用像完全二叉树那样使用顺序存储结构进行存储。Sequential storing structure can also be used to store an incomplete binary tree just like to store a complete binary tree.

C、当一棵完全二叉树是满二叉树时，叶子结点不一定集中在最下面一层。If a complete binary tree is a full binary tree, it will be possible that leaf nodes is no t on the nethermost layer.

D、完全二叉树最多只有最下面的一层结点度数可以小于2。For a complete binary tree, only the degrees of nodes on the nethermost layer could be less than 2.

E、一棵非空二叉树的为空的外部结点数目等于其结点数加1。The amount of external null nodes in a binary tree with at least one node equals to its amount of nodes plus 1.

F、满二叉树的所有结点的度均为2。All degrees of nodes in a full binary tree are 2.