What's the difference between 'fill up', 'fill out' and 'fill in'?

Understanding verb tenses is a fundamental part of mastering English grammar. Tenses tell us when an action happened – whether it's happening now, happened in the past, or will happen in the future.

Woman in red cardigan: People do get their tenses of a verb confused. Making sure that the verb is in the same tense all the way through a document or a letter or an email. If you read it to yourself ...