<s>Human: 列出一些在互联网上获取免费证书的网站。
</s><s>Assistant: 1. Coursera
2. EdX
3. Harvard Online Learning 
4. Alison 
5. FutureLearn 
6. Udacity 
7. Khan Academy 
8. OpenLearn 
9. Saylor Academy 
10. MIT OpenCourseWare 
11. Stanford Online 
12. Canvas Network 
13. Open Education Consortium 
14. Google Digital Garage 
15. Codecademy 
16. Microsoft Learn 
17. Cisco Networking Academy 
18. Learn.org 
19. Academic Earth 
20. Open Yale Courses.
</s>