"sit in" in Chinese (Simplified)
旁听参与（非正式成员）
Definition
以嘉宾或旁听者身份参加课程、会议或活动，而不是正式成员或参与者。有时也指临时加入讨论或团队。
Usage Notes (Chinese (Simplified))
常用于课堂、会议或活动，指旁听或作为嘉宾参与。英文常见结构是 'sit in on a class'。不要与名词 'sit-in'（静坐抗议）混淆。一般偏口语。
Examples
I want to sit in on your class tomorrow.
我想明天**旁听**你的课。
She was invited to sit in on the meeting.
她被邀请**旁听**会议。
Can I sit in for a while?
我可以**坐一会儿旁听**吗？
My friend loves music, so he asked if he could sit in with our band practice.
我朋友很喜欢音乐，所以他问能不能来**参与**我们的乐队排练。
Feel free to sit in anytime if you want to learn more about the project.
如果你想多了解这个项目，随时欢迎你来**旁听**。
During college, I used to sit in on random lectures for fun.
上大学时，我经常**随便旁听**一些讲座图个乐子。