If I want somebody to see my work what should I use...
Please have a look at it
Please take a look at it
If one of them is wrong then what's the reason for it? Thanks!
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Sign up to join this communityBoth of the sentences that you suggested are grammatically correct, natural and widely used. take is slightly more formal, and as such is probably used more often in writing. This is borne out by this NGram.
If you need to say please in front of it, you are probably dealing with somebody that you don't know or is your work superior, and would be more likely to adopt a formal tone and use take.
Please take a look at it
With a friend, relative or co-worker, you would probably replace please with can or could, or omit it completely, or move it to the end of the sentence, and use have.
Can you have a look at it, please?
Could you have a look at it?
Have a look at it, please.
My impression is that "have a look at it" implies more of at looking up something in a book, while "take a look at it" means, or at least feels, like more of looking at something out through a window.