We ____________ a happy family. [ ]
A. are
B. is
C. am
答案:A
城市机动车出入基地,当基地道路坡度大于多少时,应设缓冲段与城市道路连接()
A.8%
B.10%
C.3%
D.2%
深度为5的满二叉树中,叶子结点的个数为______。