past perfect tense

• I had never seen such a beautiful beach before I went to Kauai.
• I did not have any money because I had lost my wallet.
• Tony knew Istanbul so well because he had visited the city several times.
• Had Susan ever studied Thai before she moved to Thailand?
• She only understood the movie because she had read the book.
• Kristine had never been to an opera before last night.
• We were not able to get a hotel room because we had not booked in advance.
• A: Had you ever visited the U.S. before your trip in 2006?
  B: Yes, I had been to the U.S. once before.