Teach Page Posts Update

[Gracia-zhang]

Fixes #[Add issue number here]

Changes: Added 12 posts from previous submission form. (08/2020 - present)

Screenshots of the change:

[Gracia-zhang]

Hi @yinhwa , Hi @Qianqianye , Just the same update as the teach branch last time. 12 posts are updated. Please check it out. Thank you so much!

[Qianqianye]

Thanks @Gracia-zhang. Can you resolve the conflicts or maybe recreate this PR based on the latest commit?

[Gracia-zhang]

Thanks @Qianqianye, I'll do it ASAP.