[单选题]
A swimmer heading di dkmf tfstz3)0-edb)zsj/c2 5rectly across a river 200 m widwnh1pjk+5ece t/g 4, hc9t8jye reaches the opposite bank in 6 min 40 s. She is swept downstream 480 m. How fast can she swim in stil k+9y15/c4hee hjwttn j,g 8pcl water?
