I have been studying all day.
- This is the normal (and most common) way to say that I have been studying all day and now I am tired etc.
However I often meet with sentences like:
I have studied all day.
The two sentences above are perfectly normal however the thing I am struggling with is that sometimes present perfect simple "version" is not acceptable and I don´t know why. For example "I have written letters all day" is the sentence which I was told was not correct - don´t really understand what makes that huge difference compare to the sentence "I have studied all day".
I´ll give you another examples I did with my teacher:
I have used this racket (tennis racket) for 10 years.
( Now I will start using a new type) - in her opinion this sounds ok and could be used
I have used this phrase for months and nobody has ever told me it wasn't correct English.
- Here,for some reason, my teacher definitely wouldn't use present perfect simple and would prefer to use present perfect continuous - again - I don´t see much difference between this sentence and the one above.
Would it be possible to explaing me, please, why sometimes one sentence is possible and another is not even though they are very similar to each other. I´d really like to learn to use this "strange" use of present perfect simnple.
Thank you very much!