(a) If I want to say to use "good and friendly" together in a sentence, how should I write?-- Vincent, 'good' and 'friendly' just do not go together, sorry-- it doesn't make reasonable sense.
(b) Do you mean the correct sentence is " Ali was sick for the last few days".-- Yes, but these are both OK: 'Ali was sick fora few days /the l
"John and Peter are good and friendly" can theoretically mean that John and Peter are good people (i.e. of good character) and also friendly people, but there are problems.
One problem is that "good and ..." is an idiomatic expression meaning, roughly, "very much" or "completely", and this tends to throw the reader and make the sentence look odd.