"Adamo ne povis ĉeesti la konferencon en Pollando."

Translation: Adamo could not attend the conference in Poland.

[GastonDorren]

Why is 'be at' incorrect for 'cxeesti'?

[traevoli]

As in English, being at an even is not quite the same as attending it:

• La konferenco okazis ĉe hotelo. La hotelestro estis ĉe la konferenco, sed li ne ĉeestis ĝin.
• (The conference was held at a hotel. The hotel manager was at the conference, but he did not attend it.)

[cdub4language]

Would "be present at" work?

[Lohnesinpr]

ne povi unable?

[Snugglesworth]

How is this different that "Adamo cannot attend..."?

[spuddy93]

Because it is the past tense "povis" not the hypothetical "povus." Basically, the sentence is saying that the conference already happened and Adamo couldn't make it. Not that, if it were to happen, he wouldn't be able to make it.