加工箱体以铸出的主轴孔为粗基准时，其主要目的是什么？
If help has not arrived in 10-12 hours after you abandon a vessel in a survival craft，you should（）. go in one direction until the fuel runs out。 plot a course for the nearest land。 take a vote on which direction you should go。 shut down the engine(s) and set the sea anchor。
箱体零件加工时的定位基准选择时为何常遵循“基准统一”的原则？
（）是一种无特定收集用户信息指向的内容个性化方法。 规则式过滤法。 选择式过滤法。 协作式过滤法。 学习式代理技术。
简述小分类单品配置工作的核心？
For use as protection from gas leaking from a refrigeration unit，each ship must be equipped with a（）.
