The first day of the month is the beginning of a new month.

He is actually working eight hours a day.

He tried to solve the problem all day long.

The time complexity of this algorithm is O(n).

I will start the meeting at 9 a.m. Eastern European Time.

This system enables real-time operation.

We will start the meeting at 3 p.m. Central European Time.

We plan to hold the meeting in Western European Time.

He was studying all day.

He was focused on his work all day long.