21. I'll have all of the readings ______ by the end of this term if my plan goes well．
A. completing B. to complete C. completed D. being completed
22. I lost sight of Wang Ping when we reached _________ looked like a large market.
A. that B. which C. what D. where
23. As long as I can remember, _______ I called, my son would answer.
A. before B. any time C. until D. while
