He was disappointed to find his suggestions .
A. been turned down
B. turned down
C. to be turned down
D. to turn down
网友回答
A. been turned down
(答案→)B. turned down
C. to be turned down
D. to turn down
解析：他很失望的发现他的建议被拒绝了。建议与“turn down”为动宾关系所以用过去分词作补语。选B