第二部分 单项填空(共10小题；每小题0.5分，满分5分)
21.The heavy fog in London made ______deep impression on us, which was sometimes so heavy that we lost _______sight of everything around us.
A. a; the B. a; 不填 C. the; the D. the;不填
22. Is this the reason _______she explained in the report for her success in the job?
A. what B. that C. how D. why
23. When he entered the hall, he found the big desk ______with flowers and many people ______at him kindly.
A. covering, staring B. covered, stared C. covered, staring D. covering, stared
24. It was on October 3, 2011 _____ a big fire happened in Beijing, _____ was a great shock to lots of people.
A. when; that B. that; when C. when; which D. that; which
