Isolated singularities (Complex Analysis)

Locate each of the isolated singularities of the given function and tell whether it is a removable singularity, a pole, or an essential singularity. If the singularity is removable, give the vlaue of the function at the point; if the singularity is a pole, give the order of the pole.

(1) $\displaystyle \frac{e^z-1}{z}$

(2) $\displaystyle \frac{z^4-2z^2+1}{(z-1)^2}$

(3) $\displaystyle \frac{2z+1}{z+2}$

If anyone could show me how to do any of these, I would appreciate it. I don't understand it..Thanks!