be 这里为什么要用原型？

这是虚拟语气的一种情况。

在建议,要求,命令,想法后的动词后的从句里, 用should + 动词原形, should 可以省略. 如 advise, agree, command, decide, demand, determine, grant, indicate, insist, order, prefer, propose, request, require, stipulate, suggest, urge, vote.

例：She had requested that the door to her room be left open.

His defense team has requested that he （should) be temporarily released to receive care from his family at home, the investigating judges said in a report posted on the tribunal's Web site.

当前面有request要求，ask建议,recommend推荐，suggest建议，demand要求，这一类的词时，后面从句中的should 可以省略

I suggest that we (should) hold a meeting next week.
He insisted that he (should ) be sent there.

be 是虚拟语气~~~关键在那个动词request上~~像REQUEST, SUGGEST等表命令建议要求别人的动词后加从句时，that从句要用虚拟语气~~从句谓语形式为do或should do

例子 he suggested that I go home immediately~~他建议我马上回家

requested that
是一个虚拟语气 用should +动词原形
should可以省略

should虚拟