The plan just because people were unwilling to cooperate.
A. broke up
B. broke down
C. broke away
D. broke off
网友回答
A. broke up
(答案→)B. broke down
C. broke away
D. broke off
解析：考查动词短语意义。Break up打碎，分手，解体，break down失败，崩溃；break away脱离，break off折断，由题意：因为人们不愿意合作计划落空了。可知B项正确。