Video: Chinese has invented Gun powder, compass, papers and printing. Do you know Dr. Lien-teh was a Chinese-Malaysian epidemiologist who invented a surgical face mask that’s widely believed to be the precursor to the N95 mask.

Video: Chinese has invented Gun powder, compass, papers and printing. Do you know Dr. Lien-teh was a Chinese-Malaysian epidemiologist who invented a surgical face mask that’s widely believed to be the precursor to the N95 mask. 中國人發明了火藥、指南針、紙張和印刷術。 你知道嗎？伍连德博士是一名華裔馬來西亞流行病學家，他發明了一種外科口罩，人們普遍認為這種口罩是 N95 口罩的前身.
https://vimeo.com/563882517
https://youtu.be/34PFCq_B71w