I was trying to convert a rational function $\mathbb{R}(X)$ to a polynomial of type $\mathbb{R}[X,X^{-1}]$ but I failed. I searched internet and $\mathbb{R}[X,X^{-1}]$ has its own name!: "Laurent polynomials". 

My questions: 

1- Every Laurent polynomial is a *combination* of rational functions. Is every Laurent polynomial possible to be equal to a single rational function?

2- Are there methods to convert rational functions to Laurent polynomials? How are they?