English grammar_ Adverb_ fairly / rather

1> fairly

He speaks English fairly well.
He speaks fairly good English.
He is a fairly good speaker of English.
He speaks English quite well .

• fairly, 【adv.】 Fairly , Show a positive or positive attitude
  Not with too Continuous use ;

• too…to , Too much , too It's negative ;

2> rather

the hat is rather too big
This hat is a little too big .

• rather,【adv.】 Fairly , Express a negative or negative attitude ,
  Can and too Continuous use ;

• rather -》 somewhat ;