Question: Are these prepositional phrases?

[Ellie]

I am tired *of working.*

She is good *at cooking.*

I am thinking *about traveling..*

IOW, are "of,' "at," and "about" prepositions in these sentences?

[Matryoshka]

31 minutes ago, Ellie said:

I am tired *of working.*

She is good *at cooking.*

I am thinking *about traveling..*

IOW, are "of,' "at," and "about" prepositions in these sentences?

Sure, and the objects are gerunds (nouns).  You could replace any of these with regular nouns or pronouns and end up with the exact same sentence structures.  I am tired of quarantine.  She is good at chess.  I am thinking about pie.