21. _______ in the 1800s and first mass-produced in Germany, the harmonica(口琴) was designed to play simple folk tunes.
A. Being invented B. Inventing C. Invented D. Having invented
22. When McKie brings friends or volunteers to the area where she works, most of ________ spend the first day sobbing.
A. them B. whom C. that D. which
23. My arrival was timed perfectly; it was the second weekend of November, when the world largest wine auction ________.
A. held B. was being held C. was held D. was to hold
24. Since then, more than 2 billion apps have been downloaded at prices ________ free to $900.
A. ranging between B. ranging from C. rang between D. rang from
