On meaning 1, I think the top one is supposed to say "[Adjective: た form] A + ら" but it doesn't. What I see is: "[] A + ら". When I click to see examples, I see adjectives.
1. The third basic usage type When A, after A, then B--says the second clause is in non past form. But the third example sentence has the second clause in past form.
2. Another note: What about the meaning where, When A happened, surprisingly B happened. Like: 家に帰ったら、田中さんが着ていました。When I came home, Mr. Tanaka was there (unexpectedly). I mention this usage, but I also have a few questions about it: How often is this type of ‾ たらused in reality? And how can you tell if someone means this unexpected event as opposed to two events that occurred in succession in the past? I would love some light shed on this topic.
3. One more way to use ~たらis to refer to improbable things happening. Like もし有名人になったら、V-non past. If I become famous, I'll do V. Similarly, you can say しっぱいだったら、良い成績を上げなかった。If I had made a blunder, I wouldn't have gotten a good grade, implying that I did get a good grade.
3. Do you think this is (the 'improbable' bit) actually a different meaning, a more an extension of the 'if/then' formation? I'll have to ask a friend, but I'm guessing that you could probably use it to represent something that is probable as well. I'm looking at the entry in the Basic Grammar Dictionary (the big, huge grammar dictionaries you can find just about everywhere), and it makes no reference to this 'usage'.
So, I feel like this is more just an example of how an if/then or action1->action2 structure can be extended. What do you think?
3. そうですね… Okay, I think I agree with you now that these "usages" are really just extensions of the same usage. We have model sentences to show how different situations/ideas can be conveyed. Thanks!
Edit: I was just looking over my old notes and found something. The past tense usage of ‾たら always means a surprise situation. Is this really true? 例えば、 Verb A-tara + Verb B-ta (past tense) = surprise situation! 家に帰ったら、友達と一緒に映画を見に行った。X You can't say this because it couldn't have been a surprise situation. Do you see what I mean? I have this rule in my notes distinctly.. Can anyone confirm this?
One is a series of events that may or may not be cause-effect related, while one shows a cause-effect relationship.
As to なら/たら, I'll have to leave someone else to answering that - I have a very fuzzy understanding of it from soaking it up from those around me - someone that knows it on a more technical side will be better at explaining it.
I have just watched this lesson on youtube. Though the explanation is not perfectly clear to me, there doesn't necessarily seem to be a cause/effect relationship in the "tara + past tense" construction. For some reason I have been totally oblivious to the fact the #3 uses past tense. Now I wonder where I should put the example sentence I had originally written under #3, for it uses present tense. (御金を借りたら返すのが当然だ。) Is it closer to #1 or #2?