Here's some extra practice conjugating verbs in English. So many (otherwise excellent) Norwegian speakers of English make mistakes here because they forget to distinguish between the 1st and 3rd person, between the singular and the plural.
Practice conjugating verbs! Develop that "good ear" so that you can hear how bad it sounds when you get this basic part of the language wrong.
The Conjugator - Conjugates any verb you need in English, in all forms
Some terms, verb patterns and quizes to test yourself at About.com
Exercises 1, Exercises 2, Exercises 3, Exercises 4
Interactive quizes (with additional verb exercises a, b, c, d)