定语从句的介词问题That was the business meeting during which I listen

解析如下:
listen 不及物动词 后边接宾语才加"to"
That was the business meeting during which I listened carefully and kept taking notes.
试对比:
That was the business meeting during which I listened "to" carefully and kept taking notes.
the business meeting"是先行词没有错,但你没有注意到
during which = during the business meeting =when 在商务会议期间
所以先行词做的是during 后面的宾语,而不是做listen to 的宾语.所以这里listen只作不及物动词无需加"to".

定语从句及相关术语
1.定语从句：定语从句是由关系代词或关系副词引导的从句，其作用是作定语修饰主句的某个名词性成分，相当于形容词，所以又称为形容词性从句，一般紧跟在它所修饰的先行词后面。
2.关系词：引导定语从句的关联词称为关系词，关系词有关系代词和关系副词。关系代词有that, which, who, whom, whose, as等，绝对没有what；关系副词有wher...

如果listen后面接了宾语，listen才需要加to，
最常见的莫过于listen to music.或许to是省略了。
而这句话的意思是，
【我在我的商务会议期间,听得很认真,不停地做笔记】

during which 而不是to which
就是说这个
during the business meeting i listened carefully