"He stayed in the hotel."
Translation:Lui è stato nell'albergo.
In English, we use the same word "stay" to mean slightly different things. Typically when we say we are "staying" at a hotel, it just means that is the place at which we will be accommodated during our trip. In that case, the word "stare" is the right choice.
However, in English we might also ask, "How long are you staying in Italy?" And we might reply by saying, "I'll be staying there 3 days." In his case, "rimanare" is probably closer in meaning to what we are saying in English.
I guess the situation would dictate whether to use rimanere or stare. Maybe soggiornare is even better. I translated this as lui è rimasto nell'albergo and it was marked wrong..
Did he stay with friends? No, he stayed in the hotel. È stato con gli amici? No, è stato in albergo.
Did he go to the party? No, he stayed in the hotel. (rimanere) Lui è andato alla festa? No, è rimasto in albergo.
Alternatively "Ha soggiornato all'albergo." (like séjourner in French)
Am I wrong?
Wxfrog and Audra - "Essere" is the auxiliary verb went the main verb is intransitive (i.e. when the verb does not take a direct object). "Stare" is one of those verbs. You can be/stay AT or IN a place but the being or staying there is not being "done" TO it. Thus, we use essere instead of avere with stare and other intransitive verbs.
Some other common verbs that take essere: andare, venire, arrivare, partire, morire. Typically, there is no direct object with verbs of being and going, hence they are intransitive.
July 11 2020 In my view, 'rimasto' = 'remain', as opposed to 'stay', but it depends on the context of the conversation. For example: lui è rimasto nell'albergo" = 'he remained in the hotel', meaning that others with him may gone out somewhere but he chose to 'remain', or 'stay' behind. Without the full context of the conversation it is difficult to determine. I think for this exercise the sentence is infering that he 'stayed' at/in the hotel for accommodation. See comments also by LynnSerafi in this thread.
"How are we supposed to guess which DL wants?" You aren't. Just try what you think is correct based on your studies. It is okay if it doesn't match the Duo "answer", as long as you then spend some time researching and figuring out why (the Comments can sometimes - often - help us learn, but there are also many internet sources. Ideally, find a few people who speak Italian (check out Conversation Exchange) and let them help you learn Italian while you help them with their English. Alternatively, just memorize the answer and move on.