In this talk, we first recall a classical L^p (uniform) resolvent estimate established by Kenig, Ruiz and Sogge in the 1980s, it's closely related to unique continuation problems of Schrodinger operators with singular potentials. Then we turn to another type of L^2 (uniform) resolvent estimate (a.k.a Hautus-type test), which is equivalent to the exact controllability for the linear Schrodinger equation. Based on this approach, we give some recent results concerning the observability of the 1-d Schrodinger equation with potentials x^{2m}, m=0,1,2,...