In the course " Bildoj kaj Demandoj ". I met this : " Ĉu heliĝas aŭ malheliĝas matene/vespere ? " . It makes sense to me but I think it should be " Ĉu heliĝas aŭ malheliĝas mateno/vespero? " . One more thing, there is another sentence like this: " Kion faras la arbo? La arbo falas " I don't understand why the tree can itself fall while the picture shows the man makes the tree fall. So, it should be " Kio okazas pri la arbo? La arbo faliĝas. "

funfundzvanzig:In the course " Bildoj kaj Demandoj ". I met this : " Ĉu heliĝas aŭ malheliĝas matene/vespere ? " . It makes sense to me but I think it should be " Ĉu heliĝas aŭ malheliĝas mateno/vespero? " . One more thing, there is another sentence like this: " Kion faras la arbo? La arbo falas " I don't understand why the tree can itself fall while the picture shows the man makes the tree fall. So, it should be " Kio okazas pri la arbo? La arbo faliĝas. "

I had a bit of trouble with the "matene/vespere" until I learned that a time with an -e ending means "during" or "in/at/on". I think the question is asking "Does it get brighter or darker during the evening?"

As for the second part of your post, I believe that's just so they don't have to draw a different picture for every possible circumstance. If I remember correctly, they do at one point ask "Kio okazas pri la arbo?"

funfundzvanzig:Ĉu heliĝas aŭ malheliĝas matene/vespere ? " . It makes sense to me but I think it should be " Ĉu heliĝas aŭ malheliĝas mateno/vespero?

In English, we would say "Does it become light or dark in the morning/in the evening?"

That "it" is a sort of grammatical place-filler, because our sentence would sound strange with no subject. Esperanto does not always need this - whereas the Esperanto sentence "Pluvas." is a perfectly fine complete sentence, "Raining." in English seems like a semi-poetic fragment.

One could argue that it doesn't make the most sense to say that "vespero heliĝas", as vespero is just the time - it's the sky, the circumstances, the light levels which are changing. The evening is just the time in which that all happens, so an adverb of time makes more sense here.

"Vespero malheliĝas" - would indicate to me that the days are getting shorter, as it's passing midsummer, and so the evening-time is getting darker. Or some sort of metaphorical use of "hela", talking about a dark or grim feeling, perhaps.

"Malheliĝas vespere" - would indicate to me that in the evening time, it gets dark. Malheliĝas = okazas malheliĝado

funfundzvanzig:One more thing, there is another sentence like this: " Kion faras la arbo? La arbo falas " I don't understand why the tree can itself fall while the picture shows the man makes the tree fall. So, it should be " Kio okazas pri la arbo? La arbo faliĝas. "

The action of "to fall" can be thought of as something that the tree does. Whether there's an external agent causing this is extra information. The question "kion faras X" seems to prompt the answer "X [verb]..."

Kion faras la arbo?
Ĝi silentas (pro manko de buŝo) - It is silent (due to the lack of a mouth)
Ĝi staras saĝe kaj aĝe - it stands, wise and old
Ĝi falas pro homa hakado - It falls, from human chopping
Ĝi dancas en la vento - It is dancing in the wind

I would say that if you're asking "kio okazas pri" the tree, then that leaves the response able to have a subject other than the tree.

Kio okazas pri la arbo?

• Sciuro loĝas en ĝi - A squirel is living in it
  
• Homoj dancas ĉirkaŭ ĝi - People dance around it
  
• La arbaro tombe silentas - The forest is gravely silent

Final point - "fali" is already an intransitive verb, the same as in English. I'm not sure if there's any necessity in the -iĝ- affix. "La arbo falas" is fine, faliĝi seems a little bit confusing.

evanamd:

funfundzvanzig:In the course " Bildoj kaj Demandoj ". I met this : " Ĉu heliĝas aŭ malheliĝas matene/vespere ? " . It makes sense to me but I think it should be " Ĉu heliĝas aŭ malheliĝas mateno/vespero? " . One more thing, there is another sentence like this: " Kion faras la arbo? La arbo falas " I don't understand why the tree can itself fall while the picture shows the man makes the tree fall. So, it should be " Kio okazas pri la arbo? La arbo faliĝas. "

I had a bit of trouble with the "matene/vespere" until I learned that a time with an -e ending means "during" or "in/at/on". I think the question is asking "Does it get brighter or darker during the evening?"

As for the second part of your post, I believe that's just so they don't have to draw a different picture for every possible circumstance. If I remember correctly, they do at one point ask "Kio okazas pri la arbo?"

e-ending may mean anything but the problem is the sentence misses the subject " it ". So could I say " Ĉu ĝi heliĝas aŭ malheliĝas vespere?" ?

No, in the course, it is showed that the man makes the tree fall . Therefore, I think the tree is the passive matter and we have to ask " Kio okazas pri la arbo? " . But it is displayed as " Kion faras la arbo? "

As you said, the subject " it " can be omitted in Esperanto. The course I am doing is very very basic and that matter leads learners to confusion and misunderstanding. It should be explained by a few words.

A way of asking " Kio okazas pri la arbo " seems fine to me. If I say " Kion faras la arbo? " I am characterising and personalising the tree so it can be like a human being and itself fall ( in stories, poets).

funfundzvanzig:I met this : " Ĉu heliĝas aŭ malheliĝas matene/vespere ? " . It makes sense to me but I think it should be " Ĉu heliĝas aŭ malheliĝas mateno/vespero? "

Both are acceptable, but the one with the adverb is subjectless. In English that would be "Does it get light or dark in the morning/at night?"

funfundzvanzig:the sentence misses the subject " it ". So could I say " Ĉu ĝi heliĝas aŭ malheliĝas vespere?" ?

No, in Esperanto we don't use "ĝi" in the way that we'd use "it" in this type of phrase. For example to say "It's raining" you just say "Pluvas." or perhaps "Estas pluve.", but certainly not "Ĝi pluvas."

funfundzvanzig:Therefore, I think the tree is the passive matter and we have to ask " Kio okazas pri la arbo? " . But it is displayed as " Kion faras la arbo? "

If a tree is felled then it's still correct to say "the tree is falling" (la arbo falas). If you wanted to make it passive (e.g "the tree is being felled" ) then it would be "la arbo estas faligata". You wouldn't use -iĝ. "La arbo faliĝas" means "The tree is starting to fall", though note that this type of use of -iĝ for inceptive actions is not especially common and we have -ek as an alternative: "la arbo ekfalas".