车辆行驶中冷却液异常损失的主要原因是发动机（）。
A、连接水管损坏
B、汽缸体渗漏
C、冷却液温度过低
参考答案：A, B
With a lot of difficult problems ________, the newly-elected president is having a hard time.
A．settled
B．setting
C．to settle
D．being settled
一棵二叉树的繁茂度定义为R层结点数的最大值与树的高度的乘积。编写一个算法求二叉树的繁茂度。
