Writing an email to a teacher

Is it polite to send an email to your teacher during the night?

When is it a good time to send your teacher an email?

What is not a good time to send your teacher an email?

What is the correct translation of the word polite?

If you do not want to call your teacher, but have something to say or ask them, you can...

If you want to ask your teacher something while you are at home, you can...