课程中为了阐述生动而引用了来自网络的素材（图片、文字、多媒体等），故在此郑重声明：
1)本课程并不拥有和这些素材有关的版权，请转发者也注意尊重作者（版权持有人）的权益；
2)本课程是公益性课程，虽尊重作者权益，但由于成本而未能为所有素材获取授权认可，在此道歉，并敬请作者支持；
3)如果本课程使用的素材中有版权争议或引用不到位，欢迎与授课老师联系。我们会在收到意见后立即改正。
This course makes use of certain online resources, including images, texts and multimedia materials, to facilitate teaching and learning. We hereby declare the following:
1) The owner of this course doesn't possess the copyright to these materials, so please respect the rights of the original authors (copyright holders) when sharing this course.
2) This course is a public course and we respect the original author's rights. However, due to cost constraints, we apologize if any of the materials is used without your consent and we sincerely ask you for your support.
3) If the resources we used have the copyright issue or inappropriate quote, please contact with the course staff. We will correct it immediately.