Present perfect with for and since
Estrella from Spain from Burcin from Turkey writes:
  'Which is correct: I've been to Canada for ten months or I've been in Canada for ten months?' (Estrella)
'My biggest problem is use of the present perfect and present perfect continuous tense.' (Burcin)
 
 
Roger Woodham replies:
 
 
 
I've been to Canada.
I've been in Canada for ten months.
 
 Been is used in two different ways here, Estrella. If you say: I've been to Canada , that means that you have visited Canada and have now returned home. You are not still there. But if you say you have been somewhere for ten months, that means you are still there. For this reason we cannot use for ten months in the first sentence.
 
Present perfect: for finished actions important now
 
 One of the functions of the present perfect is to describe finished actions that are important now. I've been to Canada fits into this category. Study the following examples. They belong in this category too:
 
You have received a letter from the examination authorities. You are smiling because you have opened the letter and have discovered that you have passed the FCE exam.
 
Your brother has passed his driving test and has just bought a new car. You have decided to ask him for a lift to work every day
 
Present perfect: connecting the past to the present and future
 
 I've been in Canada for ten months.
Your second sentence, Estrella, tells us that you have been there for ten months, are still there and will probably remain there for some time. This is a further function of the present perfect: to connect the past with the present and to suggest continuation in the future. The following examples all illustrate this idea:
 
- Do you know Hamish?
- Of course. I've known him for years.
 
- You don't look very happy!
- I've had a headache all day and I can't get rid of it.
 
- How did the operation go?
- The doctor says I've made a good recovery and should be back at work in two weeks.
 
- I haven't seen the Smiths lately.
- No, they've moved away from the area.
 
Present perfect continuous
 
 The present perfect continuous, Burcin, is particularly useful for emphasising the continuing nature of the activity, It focuses on the length of time actions have lasted and is often used with for and since time expressions. It usually answers the how long question:
 
- How long have you been living in Canada now?
- Ever since 1992.
 
- How long have you been learning French?
- For about eight years, on and off.
 
- Have you been working all that time?
- No, I've only been working since the children started school.
 
Note the difference in use between for and since. For + time expression describes a period of time up to the present. Since refers back to the starting point.

Note also from these examples above that since as a time marker can be used as a preposition with nouns with the present perfect and present perfect continuous and also as a conjunction introducing its own clause when it is often used with the past simple. Here are some more examples of this:
 
I've had six different jobs since I left school.
But I've been out of work since Christmas.
 
I haven't smoked a cigarette since ten o’clock last night.
I've been much healthier since I gave up smoking.
 
 
    
'I've been to Canada': different uses of the Present Perfect