A. Which is better a dog or cat? And why?

Dog is better than a cat, Because I think dog is cute.

B. Do you have a yours  skateboard?

=> Corrected : The sentence is corrected grammatically. 

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No I don't have a skateboard.

=> Corrected : The sentence is corrected grammatically. 

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Minsu has a skate board?

=> Another way: Your sentence is okay and this is another way of saying it.​

Does Minsu have a skateboard?​