Ответ:

  1. Gleb usually wears simple clothes, but today he is wearing a warm sweater.
  2. Vera thinks that Gleb is very kind, and she is helping him at the shelter now.
  3. Look! Gleb is carrying heavy bags because he always helps his grandparents.
  4. I am reading this fascinating book at the moment, and I am learning a lot about true friendship.

Present Simple употреблён для привычных действий и мнений; Present Continuous — для действий, происходящих сейчас.