已知进变换炉的半水煤气中CO含量为28%，变换气中CO含量为2%，则变换率为81%。
参考答案：错
My book is _____ the table. I can't see it. [ ]
A. on
B. at
C. of
D. under
说明现代物流从业者应有的四种责任观念。
