In a construction such as, "John am disappointed with Alice", what part of speech is disappointed with? It appears to me that the "am" is a linking verb.

Similarly, "Jessica is sad", it seems to me that "sad" is the same part of speech as disappointed with.

One paper I'm reading claims that these are adverbs, but I am pretty sure this isn't the case, as "disappointed" doesn't describe "is". They feel like adjectives, but yet it's not assembled like a typical adjective would be ("Sad Jessica").

In a construction such as, "John is disappointed with Alice", what part of speech is disappointed with? It appears to me that the "am" is a linking verb.

Similarly, "Jessica is sad", it seems to me that "sad" is the same part of speech as disappointed with.

One paper I'm reading claims that these are adverbs, but I am pretty sure this isn't the case, as "disappointed" doesn't describe "is". They feel like adjectives, but yet it's not assembled like a typical adjective would be ("Sad Jessica").