Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
인간의 손은 대향성을 가지고 있어 물체를 잡는 데 유리하다.Ingan-ui son-eun daehyangseong-eul gajigo isseo mulche-reul jabneun de yuri-hada.The human hand has opposability, making it advantageous for grasping objects.