Contraction with the verb to be

Hi everybody,
I have a question.

Can I use contractions with nouns?
For exemple:

New York's beautiful.
Mary's 18 years old.
John's a cute guy.

Thanks for help.

Bye.

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1 resposta
I've already seen that kind of contraction, and as for me, I don't see anything wrong... for informal writings. I tell you this because if you wanna write a formal letter, for example, or anything formally, it has to be the other way: "NY is beautiful", "Mary is 18 years old", "John is a cute guy", and so on. Your examples are used in chats and things like that.

P.S.: espero ter escrito tudo certinho em inglês. xD