I'm not sure if I told you already but I used to live in London. (6)
I'm not sure if I told you already but I used to live in London. (5)
I'm not sure if I told you already but I used to live in London. (4)
I'm not sure if I told you already but I used to live in London. (3)
I'm not sure if I told you already but I used to live in London. (2)
I'm not sure if I told you already but I used to live in London. (1)
