why did dumbledore sound like he was pleading with snape before he got killed?

I do believe it was planned ahead. I'd be surprised if Dumbledore wasn't aware of the Unbreakable Vow Snape made with Narcissa, and that Snape had to help out Draco with his task. Thus, they (Dumbledore and Snape) had a plan in case there was no way other way to avoid breaking the vow and stopping Draco from becoming a murderer. I know people have brought up Snape's "look of revulsion and hatred on his face", but Harry felt the same in the save when he had to feed Dumbledore that potion. Still, there's no way of really knowing until we have the last book in our hands. I look forward to that day.

I don't think that he pleaded with Snape before he got killed. I think that he knew that it was going to happen. I think also that it was the pure shock of Snape on the dark side after Dumbledore trusted him for so long.

What if Snape really did not kill Dumbledore? Maybe they had an agreement so Snape did not get killed by Voltimore. In stead of begging for him to not kill him he might have been begging him to do as they planned.

I think dumbledore pleaded with snape to kill him. That is probably why they are arguing when hagrid heard them. cant wait till book 7 comes out so we will know what will happen

dumbledore really sick when he arrived at hogwart even can walk by himself.. that why he dont fight but he save harry.. it really sad.. after harry godfather and now dumbledore.. uhh harry got nobody maybe ginne can make him happy.. haha

It would remain a mystery until seventh book releases

The answer to this all depends on whether Snape is actually good or bad (in my opinion). If he was good, and if the killing was planned despite Snape's objections, then the "Severus, please" was intended to remind him of his promise to kill. If Snape was actually bad, and Dumbledore finally admitted it, the plea was indeed a plea for his life. I think that this question ultimately affects Dumbledore's character and legacy, so I think that Snape actually was acting on Dumbledore's orders. But, this is strictly my opinion. I am so eager to get book 7!!!!!!!

i think dumbledore was pleading snape to carry out his job as he knew snape won't do it unless. i think this was a prearranged between the two of them and this must have been what hagrid heard them arguing about. dumbledore wanted to have a spy in the enemy's camp and none better than snape himself who was a former DE. He wanted snape to carry it out so that he can win over the dark lord.