Yawn means to open the mouth wide and take a lot of air into the lungs and slowly send it out, usually when tired, sleepy or bored.
Solution means the answer to a problem.
Chin is the part of a person's face below their mouth.
Frown means to bring your eyebrows together so that there are lines on your face above your eyes. It shows that you are annoyed, worried, sad, or thinking hard.