题目内容：

    How long could you stand on Antarctic ice before your bare feet froze solid? A minute. Maybe two? If you’re an emperor penguin, you can do it for two months in cruel winds at as low as-75 degrees Fahrenheit1., but their special circulation acts as a kind of antifreeze to keep them warm enough.

Penguin legs and feet have evolved to lose as little heat as possible. Penguin feet preserve heat by restricting blood flow in really cold weather, keeping foot temperature just above freezing2.

Blood vessels to and from the feet are very narrow and woven closely together, cooling the blood from the body on the way to the feet and heating the blood as it returns to the body.3. .

This special ability is part of how penguins keep their eggs warm until they hatch. Each penguin egg’s father balances it on his feet and covers it with his very warm layer of feathered skin to keep it cozy while females are out feeding at sea.4.. If females haven’t returned with food by time the chicks hatch, male penguins feed their babies for a few days on a kind of "milk" made from special cells inside their throats.

5.Your hands get whiter during freezing weather because there 's less blood in them which has been redirected to the central part of your body to make sure vital organs stay warm.

A. Penguin legs work like a heat exchange system

B. Those naked bird feet may look extremely cold

C. Therefore, the male penguins must stay together in groups

D. However, parenting doesn't stop there for these devoted fathers

E. Emperor penguins also have the ability to 'recycle’ their own body heat

F. Feet get cool blood so there’s less heat to lose, while the body stays warm and comfortable

G. In fact. humans have the ability to restrict blood flow to their hands and feet in cold weather too