Which two statements are true regarding the creation of a default constructor？（） [" The default constructor initializes method variables."," The compiler always creates a default constructor for every class."," The default constructor invokes the no-parameter constructor of the superclass."," The default constructor initializes the instance variables declared in the class."," When a class has only constructors with parameters， the compiler does not create a default constructor."]
简述石漠化土地生态修复技术有哪些？
试论述幼儿教师如何才能为孩子创设一个积极的精神环境？
观察某网站监测数据，有A，B两个访客，A上午和下午分别访问了一次网站，每次访问浏览了一个页面。B下午访问了一次网站，共浏览了4个页面，请问A和B的访问次数及PV是：（） ["2，5","3，5","2，4","3，6"]
由于约束阻碍着物体的运动，所以约束必然会对物体产生力的作用，这种力称为约束（）作用。 ["剪力","内力","应力","反力"]
自由心证理论的主要内容有哪些？
