1. If you wish to audit this course, you'll need to get permission from the course instructor.2. Audit this course for five dollars and have complete access to all the course material, activities, tests, and forums.3. We encourage prospective students to sit in on a class in order to see what life is like inside the classroom at Stanford.4. It is disrespectful to sit in on a class where drop-ins are unwelcome, and you can only know if they are welcome by asking the instructor of the class.
 audit (a course) sit in (on a class)audit a course = 旁聽一門課，此課可以是網路課程，也可以是實體課程sit in on a class = 旁聽一門課，此課一定是實體課程
Would you like to buy scalped ickets to this basketball game which is sold out?