为保证在错误操作或死机时也能安全停车,一般在系统外部在设计一些如()等电路.
参考答案:紧停、保护、互锁
The police asked the little boy _____. [ ]
A. where did he live
B. where does he live
C. where he lived
D. where he lives
里 有 行李箱 很 糖 多