Traditional English prescriptive grammar teaches that these two verbs, to see and to hear, when describing their sensory nature, should never be used in the progressive aspect of tenses. Thus I ...
I'm studying Present Perfect tenses at the moment and have been wondering what tense should I use in this example: How long have you [had/been having] this thing? So I know that in some cases ...
What is the difference between the two? Why and where is the latter very strange sounding variant used?