The skills in Guild Wars 2 need skill points to be activated, and the skills can be activated completely.

You can change your professional characteristics at will in non-combat state.

Retraining lecturers can only train life skills, such as chefs and jewelers. Everyone in the game can only train two skills at a time. If you want to train other skills, you need to forget one of the existing skills, but forgetting does not mean that the skills have been learned in vain, and the life skills are still there. You can still learn them back through your tutor in the future, just at the cost of some gold coins. So all eight life skills in Guild Wars 2 can be learned.