When do you use definite and indefinite articles in Spanish?

Ladies and gentlemen, hospitals are a positive ranking. Whether there is an article or not, it is impossible to use la, only el. Un is used here because it is not specified. In fact, if we mentioned this hospital earlier, such as "Es un hospital muy grande" and then "trabaja en el hospital", there would be no problem. In short, the biggest difference between definite articles and indefinite articles is that using definite articles means that readers can know which one of the things you refer to, while using indefinite articles means that you only mention such a thing and others don't know which one.