1. necessary be necessary (for sb) (to do)
  2. need in need of; no need for; need to do; sth needs sth/doing
  3. news be in the news; be on the news; hear the news
  4. night all night; during the night; at night
  5. nightmare have/be a nightmare
  6. noise make/hear (a) noise
  7. note make/take (a) note of sth; note sth (down)
  8. notice notice sth; notice sb doing; take notice of sth; at short notice