单项选择题 About “new” and “delete”, which one is incorrect? A、“new” can be used to dynamically create objects and object arrays. B、When an object is created by “new”, the constructor of the class is called. C、If an object is created by “new”, “delete” should be used to destruct it. D、“new” and “delete” are often used in pairs, and they must be used in the same function.

单项选择题 PowerPoint文件默认的扩展名为（） A、.txt B、.pptx C、.xlsx D、,docx

单项选择题 对青春期孩子实行心理行为指导的重点是 A. 对学校生活适应性的培养 B. 加强品德教育 C. 预防疾病和意外教育 D. 性心理教育 E. 社会适应性的培养