Which, What, That, is, was, were ________ I need most at this mo

Which, What, That, is, was, were ________ I need most at this moment ________ a shower.
【正确答案】：what; is
【题目解析】：此句意思是“我现在最需要的是洗个澡”。What I need most为主语从句，因此没有先行词，而且在主语从句中又做宾语，所以直接用what, 相当于that which, 因为在从句中作宾语成分which不能省。根据时间状语at this moment可判断应为一般现在时。