训练对象是选择和确定训练方法的基本原则。
A self-contained breathing apparatus is used to（）. ["make underwater repairs to barges","determine if the air in a tank is safe for men","enter areas that may contain dangerous fumes or lack oxygen","resuscitate an unconscious perso"]
零售商开展促销活动后在明示期限内可以随时变更促销内容。（）
中药服药时间正确的是（） ["一般药物宜于饭前服","滋补药宜饭后服","驱虫和泻下药宜空腹服","健胃药和对胃肠有刺激较大的药宜饭后服"]
下面支持无线上网的Modem是（）。 ["ZXDSL 831","ZDSL 531","ZXDSL 831C","ZXDSL 852"]
什么是滑模？
