The English verb form fixes the action in time (present, past or future) but also determines how it should be regarded, e.g. whether the action is completed and/or in progress or not. This section can help make clear to you when a verb form should be used by means of contrastive exercises.
In these exercises a choice has to be made between two verb forms. This will help identify which context the verb form should be used in.
Ideally, the foreign language learner achieves a perfect command of all English verbs forms in writing, speaking, etc. If you want to find out how you are doing overall, try mix of tenses.