Thank you very much, Kim! :D

I'm confused. Not with you Adam, but with your book. And my confusion centers on this: [A friend of yours is having guitar lessons. You ask him: (how long / have / guitar lessons?) My answer: How long have you been taking guitar lessons? The keys answer: How long have you been having guitar lessons?] I'm in agreement with your answer and with Melissa. However, and also like Melissa said, their answer is also correct. I will explain. Yes, if I have a friend who is at present, learning how to play the guitar and I want to know for how long has my friend been playing, I will ask, "How long have you been taking guitar lesson?" This is common natural English. This is typically the way one would to find out the length of time of guitar learning. On the other side (you can also say, 'on the flip side'), if I ask, "How long have you been having guitar lessons?", because this is somewhat a non-standard format to learn how long, my question could be taken as I have doubt as to the friend's playing ability. My friend plays badly and I ask "How long...been having...", it would come off sounding as if my friend needs more lessons and/or should be more accomplished or should just quit guitar altogether. This is a very subtle difference between the two sentences. I hope that made sense.

Thank you for a long and very clear answer!

Hi there :-) I am a native speaker. "Been marrying" is the present progressive, so the meaning would be like, I have been doing the act of marriage constantly for X number of years. Like if you imagine a wedding that went on for a very long time :-) Also if you use marry as a verb on its own, it is really referring to the person who performed the ceremony. For example, "the priest is marrying us." But if you are talking about the state of being a married person, you always used "I am married," the past participle. Or if you are speaking in present tense, you could say, "I am getting married, right this minute." But if you're the one who is going to be a husband or a wife, "get married" is the proper verb and "to marry" is what the person performing the ceremony is doing. In response to #2, "been having" specifies the present progressive, like an action that is regular or continually happening, but it doesn't apply to possessions. So if you are asking how long you have owned anything, it is always "how long have you had that vacuum/sweater/puppy/etc. etc." The few examples that come to mind for "been having" are like, "How long have you been having nightmares? How long have you been having these horrible headaches? How long have you been having these conversations with her?" But with possessions it's always "how long have you had [the thing]?" "How long have you been taking guitar lessons?" is entirely correct. The other answer from the book is fine, too.