最佳解答: Due to the budget issue, it will be very difficult for you to add classes.
You have the following methods:
1. Take other courses. For example, if you are trying to take College Algebra and they are full, try to take other alternative courses (such as Trigonometry or Calculus instead).
2. Cross-enrollment. Some colleges allow you to make up your workload by enrolling other colleges. You should discuss this with your school for the possibility.
3. Take non-preferred class (for example, evening, morning, and weekend).
If all of these do not work, then adding the class will be your last option (which I don't think you will prefer). Each instructor has his/her own practice about adding classes. So there is no way to know if you have a great chance or not. The chance of adding is extremely low when there is a official waitlist.