Ответ:

  1. A: Why are you being in such a hurry? B: I’m worried. My exam starts in ten minutes.

    Are you being describes temporary behaviour; starts refers to a scheduled event.

  2. A: I am thinking of changing school. B: I don’t think it’s a good idea. You’ll be lonely.

    Am thinking describes a current consideration; don’t think is a stative verb expressing an opinion.

  3. A: Why are you being angry? B: My sister is always taking my clothes.

    Are you being describes temporary behaviour; the continuous form with always expresses an annoying repeated action.

  4. A: Tom looks very stressed. B: Yes. He is studying a lot these days.

    Looks describes appearance; is studying describes a temporary activity happening around the present time.

  5. A: Why are you leaving now? B: My train leaves in an hour.

    Are you leaving refers to a present arrangement; leaves refers to a scheduled timetable.