I have so many courses which are boring and useless while I have to be present. I also have lots of important work which is valuable and do good for my future crareer while I must make use of every minute of my spare time to finish them .
Almost every teacher of the boring classes would call the roll each time to show his/her value. Maybe that is the only power he/she can use. If you dare absent , you will be sorry. Sometimes, I took the book I want to read to the class but I can't concentrate. Sometimes I took half of these classes and slip away but it is easily discovered by the teacher. It's worse than you are absolutely absent.
So, I have to endure. Maybe that is the pain that every student need to suffer.