2019年襄阳的中考试试题有如此一个句子：
Most adults find it hard to remember the things happened while they were children.
这句话中的happen若是后置定语，作为不可数名词，应该不可以用过去分词，而应该用happening, 假如当作定语从句，从句缺主语，应该不可以省掉关系词，有同事说remember后面跟的是宾语从句，那整个句子意思就变成了：大部分成年人发现非常难记住当他们小的时候，这类事情发生了。跪求大神解答!
应该是：Most adults find it hard to remember the things that (或which）happened while they were children.
