Sentences using humble expressions and multiple verbs

Question

I was solving exercises from the Genki II workbook when I stumbled upon this sentence: ”私は先生に東京の大学について聞きました”. It had to be changed into a sentence using humble expressions. There appear to be 2 verbs つく and 聞く, so I thought that both of them should be changed. However, according to the answer key, only the latter one should　(to お聞きしました/伺いました). It made me wonder if in sentences with multiple verbs only the main one is changed to the humble speech, and if there are any additional things one should know when making a complex sentence using it (though I might be simply misunderstanding the original sentence).

The textbook doesn't appear to talk about this subject, and I can't seem to find an answer using google (maybe my google-fu is just too weak).

Answer 1

That idiomatic ついて is not used in the original sense as a verb (i.e. "to follow"), and furthermore, you don't have to apply your humbleness to 東京の大学.

Otherwise, you will see the like of 先生について、世話をした → 先生にお付きして、お世話をし申し上げた.

You change verbs to the humble version whose direct or indirect object is one whom you show your respect to.