The English verb think corresponds to three swedish verbs: tro, tycka och tänka, a fact likely to cause confusion for non-native speakers.
I think Peter is a teacher - Jag tror att Peter är lärare.
In the above example Peter is a teacher is statement which obvisously is true or false. Hence tro is the appropriate Swedish verb.
I think Peter is a bad teacher - Jag tycker att Peter är en dålig lärare.
Peter is a bad teacher is a subjective judgement which cannot be said to be true no false. I this case tycka should be used.
I think about you all the time - Jag tänker på dig hela tiden
Be quiet! I am trying to think. - Var tyst! Jag försöker tänka.
NOTE: Tycka om in the above case is pronounced without emphasis on the preposition. Tycka om means like. Jag tycker om pannkakor - I like pancakes.
