"To leave the dog in the car is cruel."
Translation:Lasi la hundon en la aŭto estas kruele.
I suppose the explanation is along the lines of "the course authors haven't added it and nobody has reported it yet."
That said, be careful about turning adjectives and adverbs into verbs. I've been seeing a lot of people on the discussion boards who have been led by the course to believe that this is common and ordinary -- even the "right" way to describe things in Esperanto. The same article that Jorge mentions also warns about over doing it. The normal way to describe a subject in Esperanto with estas plus an adjective. (La birdo estas blua). The alternative (La birdo bluas.) Should be treated as an alternative -- and only used for special effect.
So -- yes, you can say "kruelas" here, but there's no reason to, so it is better to say "estas kruele."
i am wondering the same - i guess it is because kruele is refering to a verb here (lasi) and not to a noun - so it has to be an adverb, and not an adjective - if kruela was an adjective here, you could write kruelas instead of estas kruela, but since it is used as an adverb, you have to write "estas kruele"
"Kruelas" pravas, laŭ PMEG: http://bertilow.com/pmeg/gramatiko/gravaj_verboj/esti.html#i-hjm
"Estas necese fari tion. → Necesas fari tion."
EDIT: The only reason I am not deleting this message is because it would also delete Salivanto's response, but to anyone reading this in the future, please pretend my comment is not there. ;-)
I think you've jumped from "necesi is in PMEG" to "krueli is OK" - when such a jump is not justified.
It's worth pointing out that necesi is a traditional verb in Esperanto going back at least to 1920... probably further back, and so is well established in Esperanto. Krueli is not.
Taking this thought a step further, necesi is actually far more common than the various forms of esti necese (estas nur necese, estas nepre necese, estas ja necese, ktp). It is also more common as a verb than as an adjective. On the other hand, kruela is always used as an adjective or adverb, for all intents and purposes.
Haha - I'm more pained by your use of "pravas".
Your progress should be encouraging to others on the board.
(To those reading along, I've gotten to know Jorge.R.Nogueras personally - which is why I'm being bold enough to say that he's causing me pain. I wouldn't talk that way to a stranger -- well, not usually.)
The easiest way to think about it is that you should use the adjective to describe a noun, and only a noun (any -O word, tio/tiu, etc.). For anything else (adverbs, verbs, entire phrases, or when there is no subject at all), use an adverb:
- La domo estas bela / Tio estas bela / Tiu estas bela.
- Naĝi la tutan tagon estas tre lacige.
- Estas pluve.
Well, mostly I was teasing Jorge.R.Nogueras... or maybe myself.
The only thing I would add is that there can't be an adjective without a noun (or an implied noun as in "la angla" = "la angla lingvo.)
- Estas bone ke vi venis - it's good that you came
- Estas malpermisate fumi en la domo = it is forbidden to smoke in the house.
- Bonege - great!
Well, yes. "accept and learn" that Esperanto is different from English -- but my understanding is that "adjectives can only modify nouns and pronouns" (which makes sens to me logically) came into Esperanto through Slavic languages - which means that if Esperanto were more like English, there would be more for other people to "accept and learn" as they learned this hypothetical alternate Esperanto.
Some grammarians call "e" a "neutral ending" (not plural like bonaj, or accusative like bonan, or singular like bona)... and this makes some sense. I'm not sure whether it makes it more clear or less clear.
For anything else (adverbs, verbs, entire phrases, or when there is no subject at all), use an adverb.
That certainly makes it a lot more appealing to me, as it removes some of the cognitive dissonance I feel in seeing what (in English) are nouns, treated as verbs (or adjectives).