问题补充：
How many of us , say,a meeting that is not important to us would be interested in the discussion?
A. attended
B. attending
C. to attend
D. have attended
答案：
A. attended
(答案→)B. attending
C. to attend
D. have attended
解析：此题中动词say为插入语，不影响句子结构，如果去掉它，我们便可清楚地看到选项动词用作介词of的宾语，us为其逻辑主语，故应选用其动名词形式，构成How many of us attending a meeting that is not...?
