Diseases of the mitral valve greatly affect the function of the heart.

He is involved in drug discovery research.

His running ability is the best in the team.

I will participate in an obstacle race this weekend.

My aunt is receiving treatment for pemphigus.

I ask the courier to send packages every week.

I sent a letter to him.

The monk wearing that hat was quietly offering prayers.

He underwent surgery due to an injury to his extensor digitorum communis.

The early autumn wind began to blow, and the leaves began to change color.