当其它系统向视频监控系统发出联动信号时，其联动响应时间不大于4s。（）
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The engine will fail to start unless （）.
A. the pressure of the starting air is high enough
B. there is enough air in the air reservoirs
C. the air is supplied into the cylinders in the appropriate sequence
D. all of the above
当门的正面刷完后用木楔固定住，再刷门背面。
A. 正确
B. 错误
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