I think example 8 is misleading. It reads and looks like neither bridge on the left is playable when you mean that ONE of the two is unplayable.
Well spotted. The German text does actually say that 'the bridges to the left can't be built like this'. I missed the German 'so' when reading it, but I think it should be clear what is intended from the rest of the sentence and the picture - which is why I didn't spot the ommission when proofreading. Thanks for pointing it out. I'll alter the file in due course.