Once upon a time, there was a big castle in this place.

Nuclear power plants are an important source of energy supply.

In this area, power generation by wind power is the mainstream.

This wind power plant generates enough electricity in a day.

In the past, we used to play in the park every day.

Once, we used to play in the park every day.

He tends to hold onto past failures.

I need to leave the house right now.

He came out of the room and started running immediately.

He spent the whole day playing games without leaving his house.