There is a difference between verbs that denote a dynamic situation—something that happens— and those that denote a static situation—a state of affairs that exists. You ruined the concert is dynamic. Sentences with dynamic verbs can be paraphrased with the expression What happened was/is that…; e.g. What happened was that you ruined the concert. Bill knew French is not dynamic. It is stative, since we cannot gloss it by saying *What happened was that Bill knew French. The verb be is most frequently used in a stative sense: John was hungry describes a state of affairs. The dynamic counterpart to this proposition is John became hungry. The verb become refers to a change in a state of affairs; processes of change are dynamic. The majority of verbs are dynamic in meaning. There are few stative verbs, though some of them, especially
be, are of very frequent occurrence.