"Your English is getting better." This is happening as we speak, your English is in the process of getting better. It doesn't mean literally right now but this is an ongoing process. You could say "Your English gets better <when something happens>" like "every time you read a book or watch a movie in English."

- Your English gets better. - Oh, thank you. Why "gets" incorrect?

Thanks.

1.That man LOOKS like your brother . ( LOOK is stative verb.Does not usually appear in Progressive form) 2.Correct. Present progressive with future meaning. 3. Correct. Person is thinking about something NOW. Present progressive for action happening right now.