Multiple Choice: 4) In which of these cases is positive work being done on the person?
a) The person leans against a wall
b) The person rides on a car around a roundabout at constant speed
c) The person jumps out of an airplane and falls downwards
d) The person pushes a lawnmower around a yard

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.

answer a fan shaped mass of sediment deposited at the base of a mountain front do to an abrupt change in stream gradient;