I rang the doorbell once.
My grandma once lived in a yellow house.
Once the bus stops, we can get on.
Please go to your bedroom at once.
Both runners crossed the line at once.
The crowd asked the singer to perform once more.
Once upon a time, a little dragon lived on a hill.
All at once, the dark sky turned bright blue.
We visit the zoo once in a while.
For once, my brother shared his blue toy.
Mom let me stay up late just this once.