arely表否定,几乎不.fairly、rather、pretty还有quite、very都是副词,表程度.强弱关系：fairly → quite → rather / pretty → very
fairly：语气最弱,通常译为“还算可以、相当地”,如I know him fairly well,but I wouldn't say we were really close friends.我相当了解他,但并不是说我们是真正的密友.
quite、rather：可直接修饰动词,如我完全同意你I quite agree with you、我们很喜欢那本书We rather like the book.其余不可以.
quite：可修饰不可分级的形容词(如right,wrong,ready,full,empty,perfect,impossible,alone,unique等)通常只用quite,此时quite并不表示“相当”或“很”,而表示“完全”：You’re quite right (wrong).你完全正确.
rather:只有 rather 可以与比较级和副词 too (太)连用：It’s rather warmer today.今天暖和多了.This one is rather too large.这个稍大了一点.【注】quite 有时也与比较级连用,但通常只限于 quite better (身体健康)这一表达中.
pretty语气与rather相当,但没有Rather正式,也没有rather的特殊用法.