Verb conjugation of "bezweifeln" in German

I ordered a cab at four o'clock in the morning which took me to the Central Bus Station. I was much to early because the bus would go just at seven o'clock. Anyway I was sitting there and listening to music.
In addition, after the tests I would like to give also a presentation to some of the teachers, as usually the different ideas come with the presentation. After speaking with them, some ideas emerge...
In the evening we saw a Dutch couple which we have met in El Calafate (in the Perito Moreno tour and who were with us on the airplane to the Peninsula). We looked for our hotel and it was OK.