"Is the crocodile more than one meter long?"
Translation:Ĉu la krokodilo estas pli ol unu metron longa?
The accusative is used with measurements: "unu metron longa" is "one meter long".
Because it's referring back to the crocodile, not the unit of measurement (unu metron), and since the verb here is esti, it doesn't take the accusative.
(Note that the reason metron does take the accusative is because it's being used as a unit of measurement. That's the way Esperanto works.)
Couldn't you put "Estas la krokodilo" or does it have to be "Cxu estas la krokodilo?"
Yes-no questions and pick-one questions ("do you want tea or coffee?") need ĉu in Esperanto.
Well, according to PIV, "longas" is not an existing Esperanto word. I even double checked Wiktionary to see if there was a relatively new entry, or it was a current neologism.
In other words no, because "longas" is not a word. Of course, there does seem to be SOME flexibility when it comes to making new words, but I guess it would depend whether or not people would agree that "longas" would mean "is long."
Salivanto has mentioned in some other comment boards about how turning adjectives into verbs is not as easy as it seems. I, unfortunately, do not know what boards off hand, so I can't link you his much better explanation of this.
according to PIV, "longas" is not an existing Esperanto word
I don't think PIV claims to include all existing Esperanto words, so just because a word does not appear in PIV does not mean that PIV "claims it is not an existing Esperanto word".
True, but it's a good practice to check PIV to see if a verb form of a word is in use before trying to use it. There is a short list of adjectives which are frequently used as verbs, and checking PIV is a good way to tell if an adjective is on that list - not foolproof, but a good first step.
Thanks. Just seeing this now.
I've written a fair bit on this topic here and there on this board, but here's kind of my final word on the topic:
I intentionally wrote it as "in favor of adjectives" as opposed to "against 'longas'" or whatever. I did not spell out all the ways it can go wrong (there are many) but focused on how to do it right.
Accusative of measurement.
Also see Mizinamo's answer to Kardelo's question from 3 years ago. It's currently the top question and the answer directly below.