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加法交换律和结合律
人教版四年级同步课，将抽象的知识点融入到趣味动画当中，使课程内容更加贴合小学生认知
一起学网校-四年级 数学-托比同步课堂5/20
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![张家口市气象台解除大雾黄色预警[Ⅲ级/较重]](http://p3-sign.bdxiguaimg.com/tos-cn-p-0015/oY3LOJfBDQooC561AcFCCP9GrBfunbAIEvgYAH~tplv-pk90l89vgd-fglass:864:486:90.jpeg?appId=32&channelId=0&customType=custom%2Fnone&from=101_middle_image&imageType=list&isImmersiveScene=0&is_stream=0&lk3s=9d3f5bff&logId=20241029153917CE348E67FA8C356F6100&requestFrom=101&x-expires=1761723558&x-signature=IT6%2Bj8%2BT1z1L5aIGSXbYabfpqO8%3D)
