My classmates invited me to the party. What if I don't want to go?

If you can't completely refuse the other party's invitation, say you want to go first, and then ask the specific meeting time. After the time is determined, you can say that you went to that relative's house or somewhere on business that day. I was busy that day anyway. Much as I want to go, I really don't have time for them to play. It can be said that I am outside now, so it is estimated that I will be a little late to attend your party. Should we eat first or get together first? Then say it again when you think it's almost over, or when asked, and then say you don't want to go. Should it be okay?