I know some ...certainly not what I would call fluent.
I was asked by my instructor a few years ago why I wanted to learn...He knew why, but he wanted to hear from me. After I explained to him my desire to be able to read and and understand for purposes of biblical research ....He stated ....99.9 % of that has been done for you and is online. If you download 4 or 5 Greek interlinear you can do the comparison. He then stated the most critical part is not understanding how to read .....it's understanding Greek grammar and Hebrew for that matter, which is quite different from English. Most of the interlinear have the parsing but understanding that will enlighten your outlook tremendously.
An example:
The Greeks do not need the article to make a noun definite as used in English. In the Greek a substantive is definite without the article……The article originally came from the demonstrative pronoun such as “this” or “that” ….which calls attention with special emphasis to a designated object. Its function is to point out an object or draw attention to it….. It is used with a word that makes the word stand out distinctly. Whenever the Greeks used the article, it points out individual identity…. and it marks a specific object of thought.
The Greeks used the article with infinitives, adjectives, adverbs, prepositional phrases, and clauses …..or even with whole sentences….. We do not have a corresponding English usage or anything even remotely similar.
When the article hē appears in Greek ….it always signals some special significance. And we need to look at the matter from the Greek point of view, not the English, if we are to discover the reason that the article is used.
(There is a critical place in 2 Thes where this is used, which alters the direction of a significant event from horizontal to vertical.)
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What you do as far as learning is up to you ...and your desires may be different from mine. But that advise and pursuit was exactly what I wanted and needed.