调车信号机何时自动关闭？
参考答案：
调车信号机在调车车列全部越过调车信号机后自动关闭。
He is said___________a book on the history of Chinese tone bridge , but I don’t know if he has finished it.
A. to have written B. to be writing C . having writing D writing
下列学者中提出渐进决策模式的是
A．西蒙
B．韦伯
C．林德布洛姆
D．埃佐尼
I don’t know if he has finished it.