I just took East Asia and Pacific Rim unit test and some of the above answers are wrong.
15. a. awkward
16. a. Orient Express
Because full names of trains and ships should be italicized.
17. d. no error
18. b. "I've left my book at home, said Emily. "May I share with someone else?"
(missing quotes after home)
19. c. "Do they have puppies here?" she asked.
20. c. Richards'
21. a. dogs's
22. b. it's
It's is contraction for it is not possessive.
Good luck on your unit test.