理论上每个PON口可以支持（）个ONU。
A、32
B、16
C、64
D、8
参考答案：C
某二叉树中度为2的结点有18个，则该二叉树中有 (2) 个叶子结点。
What does the woman mean [A] Smoking is good for the man. [B] Smoking is a bad habit(习惯). [C] Feeling is important.
