I am a student of English syntax and I have a question about complement and adjunct. In this phrase
the strong influence of Latin upon English
I would think that the PP 'of Latin' is an adjunct, while the PP 'upon English' is a complement, on the ground that the phrase above can be paraphrased into "Latin has a strong influence upon English". But when I took a kind of mock test for syntax, the answer turned out that both PP are complements.
However, I have not understood why they belong to complements, and if you have another or possible answer ( if you have the reason why they both are complements), please let me understand this problem with careful analysis and explanation.
Thank you for paying attention to my question and I hope I will get an answer soon.