sitsin Attends as a visitor (with "on") Subs 21. Run-down area Protests in a way Doesn't officially enroll Audits, perhaps Attends class without credit Attends a meeting, with "on" Acts as a sub (for) Acts as a sub Attends as a visitor, with "on" Subs at bridge Audits, with "on" Participates Jams with the band Performs as a guest Joins a jam session Audits a course, say