Broadly ‘rather’ can suggest to a greater extent and ‘quite’ to a smaller extent. You could say that a test is rather difficult by suggesting that you may find it too difficult and you could say that the test is quite difficult but not so difficult that you can’t manage it.
In ‘extremely fast’, ‘fast’ could be both an adjective and an adverb so you can say: That is an extremely fast (adjective) car or He drove extremely fast (adverb).
thanks a million for the reply. The reason for my asking this is the following: I started teaching English few days ago and I came across this question in the student’s book. The answers in the teacher’s book are rather vague (they insist on RATHER making the word after it weaker and FAST being an adverb, without even mentioning it can be an adjective too), so I got quite confused
You’ve just made my life a lot easier.
Well, there’s not much to tell, I graduated in June this year and I’ve started teaching five days ago
During the first few classes I could barely breath and talk, I was terrified, but everybody keeps telling me it’s perfectly normal and it proved to be so - it’s getting better and better.
I encourage the students to be active and ask questions and speak English in pairs and in groups. I’m giving my best to make the classes stress-free because that way they won’t be ashamed to speak, to make mistakes and they won’t trouble themselves about grammar all the time because I believe that fluency is often more important than accuracy. Do you think I’m right about this?
Best regards,