2 . Try to picture the world before refrigerators. That may be difficult!     1     They may also help store leftovers there after dinner. Yes, life today would be quite different without refrigerators. How did people keep their food fresh before these machines were around?

    2     In cold areas, ancient people could freeze their food. They could then store it in ice and snow. Warmer places allowed for drying food in sunlight. Experts say these early practices gave people the option to settle and form communities.

One advanced method of food storage arose in Persia around 400 BC. People there stored food in structures called Yakhchal, which were buildings made from mud brick to keep ice frozen during even the warmest summer months. During the Middle Ages, people stored meat by salting or smoking it.     3     These foods could then be stored in cool places, like caves, allowing people to save food for difficult times.

Later, buildings called ice houses or ice pits were built upon the idea of the Yakhchal. Such ice houses were very common by the 1800s. At the end of the 19th century, many people kept their food fresh in iceboxes made of wood.     4     Ice delivery businesses grew with more homes requiring ice to store food.

By the 1930s, many people were using electric refrigerators to keep food fresh.     5     Many refrigerators today come with built-in ice makers. Some people even choose smart refrigerators that can help them with meal plans and grocery shopping.

A．They would also dry many foods, including grains.

B．These containers held large blocks of ice to keep food cool.

C．No one knows for sure how people first learned to store food.

D．After all, kids today are used to grabbing a snack from the fridge after school.

E．Since then, growth in technology has led these machines to become more advanced.

F．With no means to store food, ancient people often went hungry or even died.

G．Actually, people found different ways to keep their food fresh thousands of years ago.

3 . On July 31, 1697, a French lawyer named Jacques Sennacques wrote a message to remind a cousin in the Netherlands to send him a relative’s death certificate. To prevent others from reading the message, the note was carefully folded, or “letter locked.” The technique was used before the invention of envelopes. However, for reasons unknown, the note never reached the recipient and was instead stored in a postmaster’s trunk, where it remained undetected for centuries. Now, a team of international researchers has deciphered (破译) the contents of the over 300-year-old sealed letter — without opening it!

The chain of events leading to this technology began in 2015 when MIT expert Jana Dambrogio got a call from Daniel Starza Smith, a researcher at King’s College London. “He asked me, ‘What would you do if I told you there was a trunk with 600 unopened letters?’”

The trunk had once belonged to 17th-century postmaster Simon de Brienne. Historians believe the post office stored the undelivered letters. That’s because, in the 17th century, it was the recipient, not the sender, who bore the postage cost. When Brienne died in 1707, he donated the trunk of letters to an orphanage. Somehow, the trunk eventually made its way to the postal museum, where it lay until recently.

Since opening the letters would destroy them, Dambrogio and her team decided to develop technology to unseal them virtually. They began by using a high-resolution X-ray scanner to create a detailed three-dimensional image of a sealed letter. While the writing inside showed up very clearly, the numerous layers of folded paper pressed close together caused the words to overlap (重叠).

To solve the issue, the researchers created sophisticated algorithm (算法) capable of deciphering the writing in the cleverly folded letter, crease by crease. The virtual opening allowed the team to read the contents “while preserving letter locking evidence.” The algorithm took almost five years to perfect. Once perfected, they used it to open four locked letters and fully decode(解码) the one from Sennacques.

1. What can we learn from the first paragraph?

A．Quite a few people could write letters.	B．Envelopes were not invented in 1697.
C．Jacques Sennacques was a postmaster.	D．Researchers couldn’t figure out the letter.

2. Why did the post office store the undelivered letters?

A．To get paid.	B．To find the senders.
C．To save the cost.	D．To scan the letters.

3. We can conclude that the folded letters________.

A．were badly damaged	B．were all decoded
C．remained very fresh	D．were very fragile

4. How did the researchers decode the letter from Sennacques?

A．Physically.

B．Chemically.

C．Occasionally.

D．Digitally.