Why Is it said that if someone is being sucked inside a black hole then he/she may see that time is running slowly?
General relativity can be used to discuss, theoretically, what happens to objects as they approach the event horizon of a black hole; it all has to do with your point of view. Outside viewers, those not affected by the gravity of the black hole, would view an object approach the event horizon slowly and pretty much never enter past the horizon. For the observers point of view time stops for the object. From the point of view of the object, its own time runs as normal, and it is the time outside of the event horizon that runs faster than normal. For more general information at a really easy to follow format you might check out What is Relativity by Jeffery Bennett.