21. Although he knew ________little about ______large amount of work done in the field, he succeeded where more well-informed experimenters failed.
A. a; the B. 不填；the C. a; 不填 D. the; a
22. --- I promise to go shopping with you if you help me with the housework.
--- ______ You are the last person to keep a promise.
A. That's great! B. How come? C. I don't agree. D. Come off it!
