If the bus started moving slowly when the passenger is boarding the same, is the passenger negligent?

No. Further, even assuming that the bus was moving, the act of the victim in boarding the same cannot be considered negligent under the circumstances. As clearly explained in the testimony of the aforestated witness for petitioners, Virginia Abalos, the bus had "just started" and "was still in slow motion" at the point where the victim had boarded and was on its platform. (Dangwa vs. CA, G.R. No. 95582, October 7, 1991)