以下关于宗法制的说法正确的是（）。 ["是奴隶制时代确定血缘关系的制度","它的核心是嫡长子继承制","它以才能论高下，主张将王位禅让给有才能的人","它维护奴隶制统治者血脉传承的纯洁性","宗法制一直到今天都在发挥作用"]
如何使用补充饲料？
A(n) （） is a special type of valve which prevents the passage of steam but allows condensate to pass. ["check valve","non-return valve","steam trap","quick closing tra"]
（）可作电动机的过负荷保护。 ["热继电器","熔断器","自动开关瞬时过流脱扣器","定时限电流继电器","自动开关长延时过流脱扣器"]
The condition where a ship on the end of a tow line is riding a wave crest at the same time as its tug rides a wave crest is known as riding in（）. ["synchronism","harmony","check","ste"]
物资采购项目的招标是怎样规定的？
