Blood donations save lives.But blood can only be stored under refrigeration（冷藏）for up to six weeks.After that,it's no longer usable for transfusions（输血）.
"Because of that limitation,people have to continually donate blood to meet the needs.But also,in places where refrigeration may not be available,that can also be a challenge.It's difficult to have blood available when needed." University of Louisville bioengineer Jonathan Kopechek says.He also says disruptions to regular blood donations due to COVID-19 have put stress on the blood supply,and COVID-19 strengthens the need for more reliable long-term storage methods.
But it's pretty rare because of all the challenges and complexities with that process.Instead Kopechek's team has developed a method of preserving blood so it can be stored in a dehydrated（脱水的）state at room temperature.To do so,they turned to an unusual preservative（防腐剂）：a sugar called trehalose,which is a common ingredient（成分）in donuts（甜甜圈）to help make them look fresh even when they might be months old,and people wouldn't know the difference.
At that point,the blood could be dried and made into a powder（粉末）.And then we can rehydrate（再水化） the blood and have it return back to normal.The team is still trying to improve yields but thinks the dried blood could be stored at room temperature for years.Kopechek says the technique could be ready for clinical trials in three to five years.If successful,it could be used to create stores of dried blood in case of future pandemics or natural disasters,and for first aid work,military operations or even missions to Mars.Maybe first aid kits on the Red Planet will include dried red blood cells.



Why we need a more reliable method to preserve blood？ ______

A. Refrigeration can't be afforded.
B. The cost to store blood is very high.
C. People can't donate their blood for COVID-19.
D. Blood can only be stored under refrigeration for a short time.

What makes the food or blood look fresh？ ______

A. Trehalose.
B. Donuts.
C. Powder.
D. The new technique.

What can we know about the technique？ ______

A. It is successful now.
B. It has been put into use.
C. It will be widely used.
D. It has been researched for 3 to 4 years.

What is the text mainly about？ ______

A. How to store blood.
B. Shortage of refrigeration.
C. A new technique of storing blood.
D. A new technique used in many fields.