He is known as the supreme leader of that country.

He tried to solve the problem all day long.

Today is my birthday.

Our store has a regular day off every Monday.

Our project is scheduled to be completed on the twentieth day of the month.

Day after day, he continued to strive to solve the problem.

He was promoted to the chief operating officer of the company.

He was appointed as the chief financial officer of our company.

He was appointed as the chief executive officer of the company.

He is the chief technical officer of our company.