Nadie tiene que ayudarse a usted. Correcciones son de su corazon por ayudarse aprender. Por eso, debe agradecerlos.

Hello Mario, I agree that it is important to leave a small note of thanks to people who correct notebooks. This is usually done from the goodness of their heart and nobody gets paid for the corrections. It is a common courtesy to say 'thank you' in situations like this. Bob