Rewrite the sentences with used to where possible. If it is not possible write impossible.
0 I was very shy as a child.
I used to be very shy as a child.
00 I hurt my back yesterday.
impossible

1 Where did you go to school?
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2 Hundreds of years ago people weren't as tall as we are now.
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3 When I was a student I sang in a choir.
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4 I saw Julia at Tom's birthday party.