A blade sharpened along both long sides. There is no blunt side to rest a thumb on, and it cuts on the way out and on the way back. Every other use of double-edged can be read off that one picture: two edges means two directions, and one of those directions may be pointing at the hand holding it.
可以想成一把兩邊都磨了刃的刀。它沒有可以擱拇指的那一面。往前推會割，往回收也會割。「double-edged」後面所有的用法，都可以從這張圖看出來：有兩個刃，就有兩個方向；而其中一個方向，可能正對著握刀的那隻手。
登入就可以看每一支怎麼連回核心畫面。