you'd better know how to use it. 你最好知道该怎么使用它

244. I can keep it?
     我可以留着吗
245. Try not to stab your sister with it.
     别拿剑刺你姐姐就好
246. If you're going to own a sword,
     这回你有剑了
247. you'd better know how to use it.
     你最好知道该怎么使用它
248. Don't listen to it. Crows are all liars.
     别听它的，乌鸦都很会说谎
249. I know a story about a crow.
     我知道一个乌鸦的故事
250. I hate your stories.
     我讨厌你那些故事

来自《权力的游戏 第一季 第三集 Game of Thrones S01E03 雪诺抵达绝境长城》第 247 行