开口系统与外界()。 ["只有能量交换,而没有物质交换","既发生物质交换,又发生能量交换","无热能交换","既无任何能量交换,又无任何物质交换"]
在Excel 2003中,不允许按行对数据清单进行排序。
简述虾维生素C缺乏病的流行情况。
Exhaust valve grooving and corrosion is caused by certain components of residual fuel oilThese components are sodium, sulfur, and (). ["vanadium","carbon","copper","ash"]
开工率低时炉头温度的控制标准可以是() ["≥950℃","≥1100℃","≥900℃","≥1000℃"]
什么是销售渠道的微观环境因素?