This is the single most important decision of your life.

There is only a single apple left.

I'd like to break this 100 dollar bill into four 20 dollar bills and twenty singles.

She embraces her singleness and enjoys her independence.

The students lined up in a single file.

He wore a single-breasted coat.

I prefer traveling on a single-decker bus.

He single-handedly built his own business from scratch.

She is single-minded in her pursuit of success.

The railway line in this area is single-track.