请问句中的介词about指什么?

题目

请问句中的介词about指什么?
The two things 【about】 which Marx was not sure were the grammar and some of the idioms. 马克思不大有把握的两个方面是语法和某些习惯用语
是不是这样?如下：

答案

翻译正确The two things about which Marx was not sure were the grammar and some of the idioms.主语 the two things谓语 were定语 about which Marx was not sure 表语 the grammar and some of the idiomsabout...