问题补充：
He didn’t make clear when and where the meeting would be held.
A. this
B. that
C. it
D. these
答案：
A. this
B. that
(答案→)C. it
D. these
解析：本题重在理解it用法，本题中it 指代when and where the meeting would be held. 在句中作make的宾语，clear 清楚的，在句中作宾语补足语。
句意：他没有弄清楚，会议会在何时何地举行。故选C
