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Would anyone kindly explain which is right ( could or shall ) and why?

(1)."John, if you work hard enough you could have an admission ticket to Michael Jackson's concert." father promised to his son.
or,
(2)."John, if you work hard enough you shall have an admission ticket to Michael Jackson's concert." father promised to his son.
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(3)."John, if you work hard enough you could have an admission ticket to Michael Jackson's concert." father said.
or
(4).."John, if you work hard enough you shall have an admission ticket to Michael Jackson's concert." father said.
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your advice will be very much appreciated!
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I would use shall for the promise and can (not could) for the statement.
CJ
Comments  
Students: We have free audio pronunciation exercises.
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you could get an admission ticket to Michael Jackson's concert, If you work hard
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