First of all, I am taking you up on all your valuable suggestions.
Wow! You had an Italian English teacher! I can imagine how those non-English Europeans who were lured by the American Dream must have gone on to study the language so hard that they overtook the locals along the way. Similarly an American lady once told how her French mother who had come over to US after the American Dream had worked her way up to have far better English skills. Children in her family were always encouraged to look up words in dictionaries. But, still the fact remains that they lived among native speakers and only that made them make it in about four years' time.
We not only have to learn new words, we need to make out the sounds of sentences when native speakers speak. I can say some sentence, but I can't make out the same sentence being spoken by Americans, every now and then, when I watch online videos. It's only when I ask you on these forums what they said in that video that I could think - Oh yes, why I didn't think that! But then they sound the way you just cannot sound! For English conversation practice I have spoken online to fellow international students. We all learners could understand each other well, but all agree that we all sound different from native speakers. That is because we could have had only learnt how they speak, formal or alike, in news and documentaries. Almost all learners don't understand 'films' without subtitles. Like it happens, one Polish girl who was in the UK looking for a job, once said, 'I just don't understand these people! They speak like 'Fa fa fa' (something like this she said). I could relate to what she was saying.
But having said that I am taking you up on your suggestion of having both printed and audio books, and especially going for the ones for the younger readers. It really makes sense. I must do it since it is from you! I have come across librivox audiobooks online. They are mostly made out of those archived online books from the American libraries. Those books before 1920, as you said, do have archaic language. But they are still understandable and enjoyable - one such author is Ella Rodman Church. But it is better to read the contemporary ones and not sound archaic! My immediate goal right now is to be able to understand and enjoy those videos that people put online nowadays, as well as enjoy books in both text and audio forms - just like you suggested.
Another difficulty is mixing up of formal and informal language. You can already see in my text how I mix all kinds of language in one without mindful of the requirement of the forum. I do have collected a few monolingual learners' dictionaries. Recent one I got is Merriam Websters' learners dictionary which has nicely got a lot of sentencs showing word usage. These sentences make dictionaries readable like books - if you don't find it strange, I would prefer reading dictionaries over others because every time I dip into one of these I always come up with having learnt something new which is very rewarding. They have got so much new to offer you. And it follows with looking the same up in different ones that I have got. Searching and readability in a software dictionary is a breeze, but then if you are holding a paper dictionary you discover so much more.
Thank you for not being terse in your replies and going that far to help us out. I wish I could run off comments the way you do! It is not that I put off or want to put off replying or asking you questions - I just have to take time thinking out how to put my comments and questions to you and still I manage to make it imperfectly and for you to have to wade through. One think I wished was to put all my questions and your answers printed out but I understand that would go against the website's interest.
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