散列表中由于散列到同一个地址而引起的“堆积”现象，是由（）

有一个散列表，共有N个槽，采用双散列探查的闭散列方法解决冲突。经过一系列插入操作，当前散列表中有M个元素，负载因子a为0.1，即M/N=a=0.1。假设M,N都非常大，并且双散列探查方法近使得每一次探查的位置，可以近似为均匀分布（即等概率地探查每个槽）。 当前对于某个关键码，近似估算不成功检索的平均检索长度（）请保留2位小数 There is a hash table of size N, using closed hashing implemented by double hashing retrieval to solve conflicts. After a series of insert operations, there are M elements in the table, the load factor a is 0.1, which means M/N = a = 0.1. We assume that m and n are both very big. And the probabilities of all the position to be probed is approximately evenly distributed because of double hashing retrieval. Now for some key value, approximately estimating the average length of failed retrieval (). Please keep two places of decimal.

B．埋刮板输送机

C．螺旋输送机

D．气吸式卸船机

B．链式卸船机

C．螺旋卸船机

D．门座式起重机

B．较简单

C．与直流腐蚀相同

D．与原电池腐蚀相同

B．SHA-1

C．RSA

D．IDEA

B．64.0

C．128.0

D．160.0

B．模式色散

C．波导色散

D．色度色散