Here are six, to get started with:

Attend means to go to a class, seminar, etc. Assist, by the way, means to help, like in basketball.

Un trabajo isn’t a work. Try paper, project or something.

A conference is the same as a convention or congress. It isn’t a talk or lecture, and…

A lecture isn’t a reading, but a talk or class.

A topic isn’t a cliche, of course, but a subject, in the sense of tema or asunto.