Helen was much kinder to her youngest son than to the others, __________, of course, made the others envy him.

A．who

B．that

C．what

D．which

串是一种特殊的线性表，其特殊性体现在（）

A.可以顺序存储

B.数据元素是一个字符

C.可以链式存储

D.数据元素可以是多个字符