Task: Question Generation
Input (English): Context: Eventually the host tree dies and rots and then all that 's left is the vine that 's now strong enough to be by itself as a strange hollow tree - thing . There was one we saw that was completely hollow and we could climb inside . When you look up you can see an opening at the top , so the whole plant is like a big straw or pipe Emma on the Bridge That walk was called the Tree Top Walk because it went to a big bridge going through the canopy .
Output (English): Why does only the vine get left behind after the host tree dies ?