see to （it） that you include （in) the examination paper (whatever) questions they didn't know (the answer) last time

又看了一下,是 the answer 不对,应改为 the answers of
全句：请务必在考卷里加上上次他们不明白答案（不会回答）的任何问题.
结构：
see to it 主句,请务必
that 引导词,后面是一个同位语从句
you（从句主语）include（谓语）in the exam paper （状语）whatever questions （宾语）they didn't know the answer of last time（作questions的定语）
先行词 questions 与定语中的 the answers 之间有从属关系,应该是 the answer of the questions,因此要加上 of