Could you please tell me the exact difference between present perfect and present perfect continuous tenses? We use present perfect continuous in a finished action with a present result. However, in present perfect tense we are told nearly the same thing. We are given the example 'It has rained. So, the streets are wet.' There is also a result here. Is this sentence true? Can we say it in present perfect continuous tense? Thank you...
The two tenses are often interchangeable. 'How long have you smoked for ?' is virtually the same as 'How long have you been smoking ?'. Both ask about your history as a smoker.
The differences often turn around, as you say, the present result. What have you been doing this morning ? "This morning, I have studied the history of France (and I have finished)" is slightly different from, "this morning I have been studying the history of France (and I might continue to do so)".
The textbook example is "I have painted this room (and I have completed it)" and "I have been painting this room (and I have not yet completed it)".