"the price for an item is too high" - not a noun phrase. Actually, this is a clause, as it has a predicate of its own.
"a bottle of water while strolling" - not a noun phrase. "A bottle of water" would be a noun phrase (a phrase that has a noun as a headword), but "while strolling" is an adverbial phrase that describes the verb "buy".
"The same brand of bottled water" - noun phrase. The headword is "brand", and all the other words cling to it and provide additional explanation.
"a pair of athletic shoes" - noun phrase. The headword is "pair".
Answer:
28) He’s worked for that company since last June.
29) “Have you been to Russia.” - “Yes, I have .” A) Had / be / haven’t C) Have / be / have
30) Have you done your homework?
31) I haven’t done it yet.
32) What are you going to wear this evening?
33) I am not going to drink/I won't drink because it is too sweet. (it could be either)
34) I’ve seen the latest Star Wars film. I saw it last week.
35) She’s written the letter. She wrote it yesterday