✔ 最佳答案
The small hole at the centre of the parachute is a channel for the air "inside" the parachute to leave slowly along the vertical axis, so the parachute can descend slowly and gently. This helps to maintain the stability of the parachute.
If such a hole is not present, the air "inside" the parachute is "trapped" there, so the descending parachute would descend at a much slower rate, and thus, more subject to instability caused by changing horizontal air-flow.
2007-01-16 20:35:15 補充：
Sorry for problems with display of the quotation marks just now..."inside&;quot; -- should be "inside""trapped&;quot; -- should be "trapped"
