1 in which he was 做 the bad situation 的定语（也就是说后面in which引导了一个定语从句）
2 在后面的定语从句中,in which做表语（he主语+was系动词+in which表语）
3 这个句子还可以说 he was in a bad situation.
He wrote a novel in which he combined the two absolutely perfectly - Lolita.
A low-fat diet is one in which less than thirty percent of a person's daily calorie intake comes from fat.
As you will see,it is a way in which you represent a variety of things about your own life.