Searching cloverleafs in a forrest III

Within Karas world there exist forrests with circuit tours in which Kara wants to go search for a cloverleaf. Every field in a circuit tour has exactely two empty neighbouring fields. One of them is behind Kara, the field Kara came from. That is, exactly one of the three question marks in the following image represents an empty field. The other two represent fields with trees: