下列关于我国国土面积、疆界和邻国的表述，正确的是（  ）

    “Years ago when I was at the Grand Canyon, I remembered someone coming up to the canyon's edge, taking a shot with a camera and then walking away, like 'got it – done', barely even glancing at the magnificent scene in front of him,” Linda Henkel, a scientist at Fairfield University, US told Live Science.

    Henkel was surprised by how obsessed (痴迷的) people are with taking pictures these days - before dinner, during friends' birthday parties, on museum tours and so on.

    They keep taking pictures because they think that it helps record the moment, but as Henkel's latest study has just found out, this obsession may prevent their brains remembering what actually happened, reported The Guardian.

    In her study, Henkel led a group of college students around a museum and asked them to simply observe 15 objects and photograph 15 others. The next day the students' memory of the tour was tested, and the results showed that they were less accurate in recognizing the objects and they remembered fewer details about them if they photographed them.

    ''When people rely on technology to remember them — counting on the camera to record the event and thus not needing to attend to it fully themselves, it can have a negative impact on how well they remember their experiences,” Henkel explained.

    But there is also an exception: if students zoomed in to photograph part of an object, their memory actually improved, and those who focused the lens (镜头) on a specific area could even recall parts that weren't in the frame.

    So basically, this study is saying that constantly taking pictures can harm your memory. But shouldn't reviewing pictures we have taken help wake up our memories? This is true, but only if we spend enough time doing it.

    “In order to remember, we have to access and interact with the photos, rather than just collect them,” Henkel told The Telegraph. However, previous research has shown that most people never take the time to look over their digital pictures simply because there are too many of them and they aren't usually very organized on their computers.

阅读材料，回答问题。
材料一 近500年来发生过三次结构性的权力转变……第一次是西方世界（欧洲）的崛起，此转变始于15世纪，在19世纪急剧加速；第二次转变发生在19世纪末美国的崛起……20世纪的全球经济、科技、文化和理念，大半时间由美国主导；我们目前正在经历的则是现代时尚的第三次权力转变，或可称为“群雄竞起”的时代。   
——（美）法里德·扎卡里亚《后美国世界》
材料二 哈佛大学的专家史迪威大胆猜测，我们或许正生活在“自我们这个物种存在以来最和平的时期”。                        
——（美）法里德·扎卡里亚《后美国世界》
材料三 不论你愿意与否，全球化进程都会不断深入地发展……甚至连反全球化也经历了一个“反全球化的全球化”过程。

（1）依据材料一，结合所学知识，概括20世纪“大半时间由美国主导世界”的因素。
（2）材料二中“当今我们生活在最和平的时期”的论断，你是否赞同？简要说明理由。
（3）综合材料一、二，结合所学知识，谈谈对材料三种“全球化”和“反全球化运动”的认识。