1. respectful = feeling or showing respect. 對某人事物發散出尊敬感的→表示恭敬的；有禮貌的 。A is respectful to B， 指A對B彬彬有禮、必恭必敬。 You get what you give. So, if you are respectful to others, you'll be respected, basically.
From that day forward, he had tried to put a respectful distance between him and Regan.
Go up to her and introduce yourself. Be polite and respectful and watch for her signals... if she's not interested, back off immediately
2. respectable (具有社會所認可的水準或品格)值得尊敬的；(令人)可敬的；很體面的
She is a respectable married woman.(可敬的女人)
Avery had a respectable career as a lawyer, and never had to be dependent on a man. (她有可敬的事業)
Even " respectable " publications such as Forbes magazine have indulged in the same sort of conspiratorial anti-Obama nonsense.
3. respected 受到尊重的 You get what you give. So, if you are respectful to others, you'll be respected, basically.