Answer:
In the middle of night, I surround the gong. In the middle of sight, I end the song
The distance from the top of your head to the floor standing up straight.
No matter how little or how much you use me, you change me every month. What am I?
Without what would everyone lose their head?
Its days are numbered.
As I went over London Bridge I met my sister Jenny; I broke her neck and drank her blood and left her standing empty.