Hi,

a) What is the slang or colloquial English used to refer to  a woman that didn't marry ?; The word 'spinster' has almost become archaic now, I never hear it. Some people tried to popularize the word 'bachelorette', but that never seemed to become used much. I'd just say 'an unmarried woman', or 'a woman who has never been married'.

b) What 's the difference between wage and salary, once both mean the same = a payment earned by a job done. (?); There's not a lot of difference. The word 'salary' tends to be used in conection with jobs that are more 'professional' in nature, eg not for a factory job. The word 'wage' usually is in the plural form 'wages'. What I hear a lot is the word 'pay' (as a noun).

By the way is it correct to write: ...both mean  the same (?); yes.

c) Here should I say: "It's not interesting for me" or "It's not interesting to me"?; You can say both, although 'to' sounds better. You could also say 'It doesn't interest me'.

d) What do we call the "adversaries candidates" when we are looking for the same job? - Contestants?; Other applicants. Competing applicants.

e)  Is it correct to say: "Please, don't forget to centralize the topic in the sheet before starting to write the story.  (?). More natural is to say 'Please, don't forget to centre your writing'.

Best wishes, Clive