Becky and Steve walked to school on a winter morning. Becky wore a hat and gloves but no scarf. Steve wore a hat and two scarves, but he didn't have any gloves. They both felt very cold.
Then Becky had an idea! "What if I trade you one glove for one of your scarves?", Becky said. "Then both of our necks would be warm, and we'd each have one warm hand. We could put the other hand in our pockets."
"Good idea!" said Steve.
After they shared the scarf and glove, they began to feel warmer.
A few minutes later Mrs. Brown appeared. "Did I just see you barter?" she asked.
Becky and Steve looked puzzled(迷惑的). "What's barter?" Becky asked.
"Barter means trade things without using money", Mrs. Brown explained. "You two traded a scarf and a glove so you could be warm. Did you know that traders bartered for thousands of years?"
"Really? How did it work?" Steve asked.
Mrs. Brown said, "Well, traders who had too much of one thing, such as salt or cloth or pigs, would exchange them with other traders for other things that they needed. Trading grew and developed, but it had problems."
"Like what?" Becky asked.
"Suppose you raised chickens. You could trade the chickens and eggs for what you needed. But if the chickens got away..."
"I wouldn't have anything to trade!"
"Exactly!" said Mrs. Brown.
"Now you see why people began to use money to trade." Mrs. Brown added.
"Is it true that silver and gold coins were used before paper money?" Steve asked.
"Yes, but they were too heavy to carry." Mrs. Brown said. "People then began to write promises on paper instead of trading coins. That was how paper money got its start."
"Wow!" said Becky, "but I guess people still trade sometimes, the way Steve and I did today!"
① exchange objects ② use coins ③ use paper money
A. ①②③ B. ③①② C. ③②① D. ②①③
