They used to make to meet and have a party at the end of a month.
A. a rule
B. it a rule
C. it rule
D. them a rule
网友回答
A. a rule
(答案→)B. it a rule
C. it rule
D. them a rule
解析：考查代词。本题考查it作形式主语，真正的主语为不定式to meet and have a party at the end of a month，rule为可数名词，故选B。