there is someone to turn to ; turn to 整个作 to do 结构里的do?

题目

there is someone to turn to ; turn to 整个作 to do 结构里的do?
It's comforting to know that there is someone to turn to when one needs help.
为什么要 turn to
只一个turn不行吗
turn to 后 怎么不加个宾语呢

答案

turn to sb (for help) 向某人求助 作求助接 turn 不及物动词 to不能省略不定式 和前面的名词 构成主动关系,用主动表示被动语法点：There ＋be ＋n.＋to do在此句型中,用来修饰主语的不定式,可用主动式,也可用被动式...