4k00:17Young scholar viewing lesson on the web and learning from home. Younger female using notes while checking out computer screen next professor undertaking math on online video simply call. Female scholar researching from home 甲醛是一級致癌物質，人類如果吸入過量甲醛，有可能會引致眼澀、頭痛、呼吸困難、失眠的問題，嚴重者還會鼻咽癌、血癌、腦瘤等，孕婦也有可能流產或誕下畸形兒。 hd00:... https://richardz976yjt6.wikiconversation.com/user