主要内容：
Fairly

She’s fairly pretty/smart. I speak English fairly well – enough for everyday purposes.

Quite

He’s lived in London, so he speaks English quite well. I quite enjoyed myself at your party. The room was quite a mess.

Rather

How was the film? – Rather good. I was surprised. He speaks English rather well. People often think he is a British-Born Chinese. It was rather a disappointment. He’s rather a fool. He had a rather good idea & He had rather a good idea.

pretty

Things are looking pretty good! You are driving pretty fast.

Considerably /significantly/ Extremely /enormously/incredibly/unbelievably/exceedingly/remarkably/astonishingly

Fairly < quite < rather=pretty