where T=transmission coefficient,R=reflection coefficient and A=Absorption coeff. and all depend on material and wavelength of radiation you are talking about..
So for any material, if T is to be high, A and R need to be low...
Since metal surface has a lot of free electrons, when the radiation strikes the material, the free surface electrons start oscillating and in the process they emit the radiation which falls on them (oscillating charge will emit radiation). This is how metals are supposed to be good reflectors..
Absorption is something i'm not very sure of but since glass has high T, obviously its A is low for visible radiation..
p.s: i could not read the previous posts due to lack of time so i'm sorry if i'm repeating something.. :)