A common difficulty for Norwegian learners is to distinguish between the different “thinking” words. Using the right word for the right context is not always easy–at least if you’re worried about offending people.
jeg tror = I think, but only in circumstances for which you are uncertain about something. for example, “I think he is 32 years old”–implying that you don’t know for sure (if you did, I suppose you would say “I know he is 32” or simply “he is 32”). as a result, it is mildly offensive if to say something like jeg tror du er pen (“I think you’re pretty”): the uncertainty in the word tror implies that you are either unsure or lying.
interestingly one uses the same word for religious belief: jeg tror på gud = I believe in god.
jeg synes/mener = I think, in the sense of “in my opinion”. So you can safely use this one if you want to say that “I think he is nice”.
jeg tenker på = I think about, as in, the actual process of thinking (“I think a lot about work”).
Only after a year do I actually get it. Or at least I recognize now when I’ve used the wrong one. (Knowing is half the battle, right?)