Shaking

I have a 1996 honda accord with 140k. I having a problme with it shaking when braking between 40-20. It shakes very hard. At any other speed its fine. I had the rotors replaced about a year ago but still have suspect they are worped. I also think that is the alignment. It only does it when braking if it is the rotors do the have to be turned when I purchase them