【单选题】High Dive Cheryl Sterns aims to go boldly where no human has ever gone before in a balloon: 40 kilometers up into the atmosphere. (46) No one has ever leapt from such a height or gone supersonicl with...
A.
It will handle several major hazards.
B.
Escape suits are tough enough to stand the atmospheric pressure of the upper stratosphere.
C.
From there, she’ll take a death-defying leap back to Earth at supersonic speed.
D.
“In 30 seconds, I’ll be going Mach (马赫) speed,” said Sterns.