玉米单株人工自交产生的后代中常常出现一定比例的白化苗,这是由于()。 ["隐性基因纯合所引起","强迫自交能够使基因突变率上升","染色体畸变所引起","异花授粉改为自花授粉后所出现的生理反应"]
污水汽提塔中,从上到下,气相中H2S分压越来越小,相应的污水中H2S浓度越来越()。 ["低","高","变化不定","稳定"]
试述板中主要钢筋的种类?
When a flash-type evaporator is to be secured for an extended period of time, the entire unit should be drained, cleaned, and (). ["completely filled with saltwater","filled with de-scaling compound","tightly closed to exclude air","vented to the atmosphere"]
企业、事业单位、机关以及其他组织中以()的劳动者,不分民族、种族、性别、职业、宗教信仰、教育程度,都有依法参加和组织工会的权利。 ["工资收入为主要生活来源","与用人单位建立劳动关系","工资收入为主要生活来源并且与用人单位建立劳动关系","工资收入为主要生活来源或者与用人单位建立劳动关系"]
简述会展合同违约行为。