简述如何预防植物组织培养中产生玻璃化现象？
The place where a channel moves from along one bank of the river over to the other bank of the river is called a（）. ["draft","cutoff","draw","crossing"]
下列关于项目控制的描述不正确的是（） ["项目控制是为了保证项目计划的实施和项目总目标的实现而采取的一系列管理活动","项目控制不包括问题发生之前采取的预防措施","项目控制有正规控制和非正规控制","项目控制可以采取多种形式，各种类型"]
作文训练是积蓄材料、思维、语言的统一。
The ocean bottom that extends from the shoreline out to an area where there is a marked change in slope to a greater depth is the（）. ["abyssal plain","continental shelf","borderland","offshore terrace"]
根据预防伤亡事故的原理简述事故的预防对策？
