time expression without particle

What is done at night comes to light by day.

Why does the moon shine at night?

She had a terrifying expression on her face at that moment.

That year, she had the entire summer off.

She felt very ill that day.

She was playing the piano at the time.

She was playing with her younger sister at the time.

In the evening, I walk with my dog.

Mother always gets up early in the morning.

The peace talks will begin this week.

She was doing the laundry at the time.

Yumi studied English last night.