1. [单选题]Each ship shall carry on board a ship security plan approved by
A. the chief engineer officer
B. the master of the ship
C. the manager of the company
D. the Administration
2. [单选题]活塞环在工作中产生“跳环”现象是指________。
A. 环紧压环槽上平面
B. 环紧压环槽下平面
C. 环悬浮在环槽中
D. 环交替紧压环槽上下平面
