exchange at discount

例句：

1. 1.They exchanged their old clothes for new ones.
   他们用新衣服换了旧衣服。
2. 2.The company exchanged its shares with the government.
   公司将其股份与政府进行了交换。
3. 3.Exchange rates fluctuate frequently due to fluctuations in the global economy.
   由于全球经济的波动，汇率经常变动。