电影《天雷勾动地火》书籍摘要：‘How do those hats work, then?’ said Hermione, distracted from her homework and watching Fred and George closely. ‘I mean, obviously it's some kind of Invisibility Spell, but it's rather clever to have extended the field of invisibility beyond the boundaries of the charmed object ... I'd imagine the charm wouldn't have a very long life though.’封勒听见了这话，刚才还很好的情绪一下子又降临到冰点，极乐之后又来了打击，让他有种透心凉的感觉。……
