The error in the possessive construction is that, instead of passenger's, it should be "passengers'". The apostrophe should be after the letter "s" because the noun is in the plural form. The correct sentence would be "Passengers' concerns about cell phone use on planes are justified."
Answer:
I think it's compound. Not sure.
An auditory learner learns best by listening or talking, so the best way for him to process is notes would be for him to read them out loud.
Is a great singer. I think. I might be wrong.
