垫铁按其形状分有()垫铁和()垫铁两种,斜垫铁的坡度一般为1/10~1/20。
参考答案:斜;平
I have been away from my hometown for years. I my family very much. [ ]
A. teach
B. see
C. talk
D. miss
设一棵完全二叉树共有500个结点,则在该二叉树中有 【1】 个叶子结点。