{"p":"can-20","op":"mint","tick":"can","amt":"1000","rows":[{"df":"qa","content":[{"q":"How do you ensure the validity of transactions and expiration time in a blockchain?","a":"Consensus mechanism: Blockchain employs a consensus mechanism to ensure the validity of transactions. In the case of Bitcoin, the consensus mechanism is based on the proof-of-work (PoW)  algorithm, which requires miners to solve a complex mathematical problem to validate transactions and create new blocks. This"}]}],"pr":"1461d35fd05681c490f33ccdb3f040618401884be60456509a35dee5df63f2f6"}