Irregular verbs: put and split
Irregular verbs were a big thing back in school, and many people got into trouble for not remembering them. In fact, they are among the first things you learn when getting started with the English language. Remarkably, despite many years of training, many advanced speakers use incorrect forms such as putted (which is only OK if used in connection with golf) and splitted. So maybe it is time to brush up on those irregular verbs?