SPOT THE MISTAKE!

The following sentences contain an error. Identify it and rewrite the sentences.

1) What nice idea!
2) We should all do an effort.
3) I didn’t say nothing.
4) People here is very nice.
5) May I have a glass of water? I’ve very thirsty.
6) I want to talk to you and so Mary does.
7) How old are you? I have 45 years.
8) I’d rather to go to the cinema.
9) They don’t know where you live, don’t they?
10) My father is engineer.
11) If I’d were him, I’d eat less.
12) What a pity! I just lost the bus!