Everyone knows that _____ is dangerous to play with fire, but _____ is difficult is to prevent children from playing with fire.
It was not _____ she took off her dark glasses _____ I realized she was a famous film star.
If we work with a strong will, we can overcome any difficulty, _____ great it is.
The man ____ visited our school yesterday is from London.
The woman ____ is talking to my mother is a friend of hers.
Because of my poor memory, all ____ you told me has been forgotten.