He was studying all day.

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

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

Today is my birthday.

He tried to solve the problem all day long.

Our store has a regular day off every Monday.

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.