Correção de texto: The old woman

There was once an old woman who knew how to ride a bicycle. Everyday, she would go by the the mountains in the bicycle, with a big bag behind her. Customs officers - all old and smart - started to suspect the old woman. One day, as she passed by in the bicycle with a bag behind her, a man ordered her to stop. The old woman stopped, then the officer questioned her:
'Listen, old woman, you pass here every day carrying a bag. What do you have inside the bag?'
The old woman smiled, showing the small tooth that had still remained, and answered:
'It's sand!'