Every year millions of tourists visit the Tower of London. The black ravens are one of the reasons why visitors come to the Tower. The ravens appeared in the fortress many years ago. According legend at least six black ravens must always live in the Tower. If the ravens leave the Tower, the country will disappear. To prevent the birds from flying away, their wings are clipped every three weeks.2. The visitors want to see the ravens in the Tower, don't they ? - Yes, they do .3. The ravens that live in the Tower are of different colours, aren't they? - No, theyaren't .4. The ravens flew to the fortress not long ago, didn't they? -No, they didn't .5. The ravens can't fly away, can they? - No, they can't .