1. 列席(会议),旁听：shut out 把...排斥在外 | sit in on 列席(会议),旁听 | sit up 不睡,熬皮;坐直

2. 列席;旁听：sit for 参加 | sit in on 列席;旁听 | ever so 非常,极其

3. 出席：sit heavy on 负担过重 | sit in on 出席 | sit in 参加

4. 旁听：sit down 坐下来 | sit in on 旁听 | sit up 坐起来,夜间不睡

1. 旁听(课程);列席(会议)
    If you sit in on a lesson, meeting, or discussion, you are present while it is taking place but do not take part in it.

    e.g. Will they permit you to sit in on a few classes?...
           他们会同意你旁听几节课吗？
    e.g. People can sit in on meetings, even if it's not really in their subject area.
           即使不在其研究专题范围之内，人们也可以列席会议。