-The captain（船长）of the Sewol ferry（岁月号）hardly do anything to help the passengers on the ferry。          ？

-              ，so over two hundred people lost their lives in the accident。

A．didn’t he； Yes

B．did he；Yes　

C．didn’t he；N0

D．did he；N0

计算题：列车管定压为500KPa时，最大有效减压量规定为140KPa。求此时闸缸的压强。