Ответ:

  1. If you want to write a novel, you should have a strong imagination.
  2. Tom Sawyer and his friends were looking for adventure in the cave.
  3. Miss Marple is a(n) fictional detective.
  4. The police started a(n) investigation into the crime.
  5. Dr. Watson was Sherlock Holmes’ loyal friend.
  6. Colin Dexter created a fictional character that became popular with readers.
  7. Sherlock Holmes is famous for his neat appearance.
  8. The police try to solve the mystery of his disappearance.