为了使市场调研方案具备一定的控制功能和机制,就要使该方案具备较好的()。
A.灵活性
B.经济性
C.指向性
参考答案:C
Instructions for on-board maintenance of each life-saving appliance shall not include().
A.a checklist for use when carrying out the inspections
B.list of crew members
C.maintenance and repair instructions
D.schedule of periodic maintenance
为了降低管束与壳体的温差应力,可以在壳体上设置()。