下列关于太阳和冷凝模型表述中，正确的是（） ["太阳系在最初阶段是一团炽热气体状星云","原始太阳系呈圆盘状，其中心到边缘有一个很大的热梯度","冷凝模型是解释地球形成的关键","美国华盛顿大学的波多塞克提出了陨石的“冷凝模式&rdquo"]
磷肥在（）性质的土壤中易发挥肥效。 ["中性","碱性","不确定","酸性"]
Which statement is true, as relates to classful or classless routing?（） [" Automatic summarization at classful boundries can cause problems on discontinuous subnets"," EIGRP and OSPF are classful routing protocols and summarize routes by default"," RIPv1 and OSPF are classless routing protocols"," Classful routing protocols send the subnet mask in routing update"]
下列关于广告标题分类叙述错的是（）。 ["直接性标题","间接性标题","导入性标题","复合性标题"]
幼儿园教育环境
教育生态学
