【英语时差8,16】空中舞蹈（在线收听）

 By bending arms and legs or angling her body–presenting more or less surface area to the ground–she can change her rate of fall, slowing or speeding up her terminal velocity around ten or twenty miles per hour. To fall as fast as two hundred miles per hour, a skydiver goes into either a diving or a standing up posture. This presents the least surface area downward, so her terminal velocity is highest. How Skydivers Land When a skydiver opens her chute, she’s increasing the amount of surface area she presents to the ground dramatically. Her terminal velocity slows enough for a soft landing.