给画线的字选择正确的意思。
自然之道 [ ]
A.道路。
B.道德。
C.规律。
答案:C
They've kept up a friendship with the teacher whom they were at school _____ twenty years ago.
A.with
B.about
C.since
D.till
对于长度为n的有序线性表,在最坏情况下,二分查找需要比较log2n,那么顺序查找需要比较的次数是 【2】 。