{"p":"can-20","op":"mint","tick":"can","amt":"1000","rows":[{"df":"qa","content":[{"q":"How to prevent double-spending attacks in blockchain?","a":"Longest Chain Principle: Nodes in the blockchain network choose the main chain based on the longest chain principle. Attackers  need to compromise most of the nodes to alter transaction records, which makes double-spending attacks less feasible."}]}],"pr":"7edf8ed56ace76b5c448cde1f4d3c1b927b9584f630efab5b9b47373c2f6a0b3"}