You may remember how to form yes-no questions with the verb 'be': switch the verb and the subject. "You are Japanese." becomes "Are you Japanese?"
To form yes-no questions with verbs other than 'be', put the helping verb 'do' at the beginning of the sentence.
- I know you. → Do I know you?
- You live here. → Do you live here?
- We eat dinner late. → Do we eat dinner late?
- They speak Italian. → Do they speak Italian?
To respond 'yes' to these questions, say "Yes, I / you / we / they do."
For the third person singular (he, she, it), the helping verb 'do' becomes 'does' to agree with the subject. Put 'does' at the beginning of the sentence and use the main verb in its basic (without -s) form:
- He knows French. → Does he know French?
- She eats meat. → Does she eat meat?
- It often rains here. → Does it often rain here?
Remember that the helping verb 'do' changes to 'does' in the third person. The main verb stays in its basic form. So don't add an 's' to the main verb! "Does he knows French?" is wrong.