It was a bit doubtful at first, but it to be a really good idea.
A. turned up
B. turned in
C. turned out
D. turned down
网友回答
A. turned up
B. turned in
(答案→)C. turned out
D. turned down
解析：考查短语辨析。turned up出现，turned in 上交，turned out 结果是，证明是，turned down 拒绝，句意：开始有点疑问，但是结果证明真得是一个好主意。所以选C。