{"p":"can-20","op":"mint","tick":"can","amt":"1000","rows":[{"df":"qa","content":[{"q":"How to prevent the double-spending problem in blockchain?","a":"To prevent double-spending, network nodes only accept the first transaction to arrive, and the second  transaction is rejected."}]}],"pr":"747188a5841b195aaada3dbd8f9c12fc0dcc97cddd72f05cc7b9c920e62f81ff"}