1. Action verbs need s at the end with third-person, singular subjects.
Example : He eats bread. / She walks to the station.

2. Negative sentences need do not, does not, or did not.
Example : I do not eat bread. / He does not eat bread.

3. Interrogative sentences begin with do, does, or did.
Example : Do you eat bread? / Does he eat bread?

4. Do not can be shortened to don't, does not to doesn't, and did not to didn't.
Example : I don't eat bread./ They didn't finish it.