Miland:'On TV' is a bit tricky because the word 'on' is used idiomatically in English...
Two other possibilities that come to my mind are
Mi rigardas al "Star Trek" televide (thus bypassing the need to choose a preposition)...

Generally preposition + noun = adverb, so rather than using "sur" or (even worse in my opinion) "je", in the past I've used

Mi vidis (ion) televidile.

On a side note, the preposition + noun = adverb transformation can usually replace the usage of "je" in situations where the preposition is idiomatic in English and you're not sure which one to use. And, kind of oddly, I actually find it more understandable. Whenever I see "je" I always feel like something is being slightly obscured, whereas the use of the adverbial style always seems perfectly clear to me.

RiotNrrd:Whenever I see "je" I always feel like something is being slightly obscured, whereas the use of the adverbial style always seems perfectly clear to me.

Je is certainly saying 'I don't know which other preposition belongs here'. If we use an adverb for that reason, then unless we are quite satisfied that the context makes the meaning clear (as here), we are sweeping the problem under the carpet. So sometimes I think we may have to be careful about this.

Miland:Je is certainly saying 'I don't know which other preposition belongs here'. If we use an adverb for that reason, then unless we are quite satisfied that the context makes the meaning clear (as here), we are sweeping the problem under the carpet. So sometimes I think we may have to be careful about this.

No argument from me - one must always be aware of whether or not clarity is being sacrificed.

That said, however, I find that when I hit "je" in a sentence, I often end up pausing and trying to guess which preposition was "really" meant. When using the adverbial style, that doesn't seem to happen, and I've found that the context almost always makes the meaning clear.

ALMOST always. But not necessarily always. No doubt it is possible to construct examples where "je" is the clearer choice, or where the adverbial method simply doesn't work grammatically and "je" is the only workable option. Nevertheless, I personally find the adverbial method preferable (where it can be used), and generally avoid "je" like the plague if I can get away with it.

What I find odd is that "je" and the use of the adverb is, from a practical standpoint, essentially the SAME THING (since in both cases a preposition with a definite meaning is not to be found). But the adverbs never cause me to pause whereas "je" almost always does. I have no explanation as to why that might be.

The preposition "je" is not the only one that gives me a bit of trouble. Three others that I can think of right off are "pri, sur, en".

It may be just a Southern U. S. idiom, but I am used to saying/writing "The boy is standing in the street." Esperanto wants "La knabo staras sur la strato" which makes sense when you think about it. "Sur la ĉielo" also sounds strange to me and it doesn't make sense. But that's what Esperanto grammar requires. My instinct tells me that it should be "en la ĉielo".

"Pri" (about, concerning, upon, on) is easy to use in some situations but sounds awkward in others. Usages like "Ni parolas pri la vetero" and "...pri tio" are fine, but other times when "pri" is used, it doesn't sound right even though it probably is right.

I guess that prepositions become difficult any time you try to translate between one language and another.

Veering away from prepositions, the verb "esti" obviously means "to be" but it also has the meaning "there is/are". Is "esti" the only infinitive that can be used like this, without a definite subject? I saw someone using "Povas esti..." in one of the Esperanto forum recently. I suspect it is incorrect but I can't prove it.

jawq81:"Sur la ĉielo" also sounds strange to me and it doesn't make sense. But that's what Esperanto grammar requires. My instinct tells me that it should be "en la ĉielo".

If you were to say "en la ĉielo" I doubt that anyone would consider it an error.

other times when "pri" is used, it doesn't sound right even though it probably is right.

Can you name a few examples?

Is "esti" the only infinitive that can be used like this, without a definite subject?

No. Most of those verbs relate to the weather. "Hodiaŭ pluvas" is the most common example. Variations of "Sunos morgaŭ" could also appear.

I saw someone using "Povas esti..." in one of the Esperanto forum recently. I suspect it is incorrect but I can't prove it.

No, it is correct. Let's see an example of a sentence with "povas esti":

"Povas esti, ke vi pravas".

In this sentence, "(ke) vi pravas" is the subject, and the verb is "povas esti". With "ke" you introduce a subsentence that works logically as an object, or a subject. Most of the times it is used for objects, like for instance:

"Ĉiuj scias, ke hundo estas besto."

But it can also be used for subjects. Another example could be "Plaĉas al mi ke vi helpis min". The subject of "plaĉas" is "(ke) vi helpis min".

Of course all the above also applies to "devas esti". Same reason.

jawq81:Is "esti" the only infinitive that can be used like this, without a definite subject?

Another verb often used in this manner is 'ŝajni':

"Ŝajnas al mi, ke ĉi tiu frazo estas ĝusta."

jawq81:I am used to saying/writing "The boy is standing in the street." .. My instinct tells me that it should be "en la ĉielo". I saw someone using "Povas esti..." in one of the Esperanto forum recently. I suspect it is incorrect...

Personally I don't have a problem with people standing en la strato (although sur la vojo may express the idea of jaywalking more clearly).

Nor would I be against the sun shining en la ĉielo. After all, we have Patro nia, kiu estas en ĉielo! The usage of sur as you describe is, IMHO, only a matter of convention. I wouldn't worry about it except to be aware (as you are) that it is used that way. Cf. PMEG (12.3.4.13, 2nd box, 2nd example)

Povas esti is simply 'Could be'. It might not be a complete sentence, but as spoken Esperanto, I would say that it's no more wrong than the English expression.

Thanks for the responses, but now you have me wondering about some things.

I know that Esperanto, being a living language, is evolving. I also know that the internet has done wonders in spreading the use of Esperanto. But I am now wondering if it isn't evolving faster than I realize.

I have copies of Butler's Step by Step in Esperanto and Jordan's Being Colloquial in Esperanto. I have also downloaded files of The Esperanto Teacher, by Helen Fryer and A Complete Grammar of Esperanto, by Ivy Kellerman. Both of these last two are old courses from Project Gutenberg and are definitely dated. I also try to use the PMEG and the Reta Vortaro.

But I try to use examples taken from grammar resources to provide guidelines on how I compose sentences. For example, I have been taught that where I might use "in the street" or "in the sky", Esperanto would use "sur" as the correct preposition. The noun ĉielo can be translated as sky or heaven and, having long ago memorized the Lord's Prayer, I would translate "kiu estas en ĉielo" as "who is in heaven". So, "sur/en la ĉielo", but "en ĉielo".

And yes, I knew how to use esti, ŝajni and the weather verbs. But I wasn't aware that you could use 'povas esti' this way.

But my point is this: apparently I am trying to adhere too closely to the rules, to examples of usage that I have studied. Is Esperanto usage changing so fast that almost anything that can be understood is acceptable? You don't need to take that sentence absolutely literally and start providing a multitude of examples. I meant it in a general sense. Someone, it was 'danielcg', told me that I should use the dictionary less and try building words with affixes more. Good advice, I'm sure.

It just seems that the rules of grammar and correct usage change as soon as I learn them. That's a bit confusing, to say the the least. And it is something that I am going to have to work out for myself. I have a tendency to be a perfectionist. Maybe I should just relax and "let it flow" and leave more of the load of translating to the reader.

Esperanto is in my opinion evolving quite slowly. Even though the most enthusiastic beginners are constantly pushing for reforms and revisions of this or that grammar rule, none of them have taken hold (that I know of). What manages to pass through so far is mostly neologisms and not much else. This doesn't mean that the language hasn't changed in recent times, it did change, but mostly through addition, and not modification. I believe erinja (and quite possibly other experienced speakers) knows more than me about that.

There are situations in most languages that I know of, when a certain form has become so widespread that by using a different form you wouldn't sound right (I know that this must also be happening with me and my use of English . Esperanto makes no exception, but still, in my experience, it grants a wider latitude of freedom than most ethnic languages do. And Esperanto has witnessed changes in those forms as well. You might have read somewhere that in the early days of Esperanto, Zamenhof used to place adjectives after their noun(s) ("lingvo internacia"), but now the opposite is far more common, and even though it would be perfectly correct for them to do so, if someone consistently placed adjectives after nouns, I would think that they are trying to break free of the mainstream, to create a personal style.

I think -- but I might be wrong -- that you are clumping together proper rules with these widespread conventions.

Is Esperanto usage changing so fast that almost anything that can be understood is acceptable?

This is IMHO a very interesting point. Most speakers are perfectly willing to tolerate almost any kind of mistake made by beginners as long as what comes through is still understandable. On the other hand, those who wish to improve their command of the language could find out that there are forms and expressions that they are not using properly. So I think that your sentence is both true and false. Almost anything that can be understood is "acceptable", at least at a conversational level, but not necessarily correct.

What I can say however, is that if you like the language enough to be ready to practise it and use it as often as you can, you will improve naturally. This doesn't mean that you should stop posting here if you have doubts. Just do not try to solve it all at once!

I wasn't aware that you could use 'povas esti' this way.

As I said, you are not exactly using "povas esti" in the same way as you are using "pluvas". With "povas esti" there is a subject (usually it is a whole sentence, unless it is something like "tio povas esti"), with "pluvas", there is none.

By the way, you mentioned doubts about the usage or meaning of 'pri'. If that is still a problem, I'd be happy to help.

jawq81: I also try to use the PMEG ..

The reference I mentioned says "Sur la ĉielo staras la bela suno. Oni rigardas la ĉielon kiel surfacon super la tero. Pri ĉielo oni povas ankaŭ uzi en." I translate: "On the sky stands the beautiful sun. We regard the sky as a surface above the earth. Concerning the sky we can also use in." (My italics for the last proposition in both cases, for emphasis)

If you want a more precise and grammatically correct way of putting what someone meant by Povas esti (which I would regard as a colloquial form, not a grammatical model) I could suggest Eblas.