它給了我混音的錯誤。我不知道為什麼！你們能幫忙嗎？

pragma solidity ^0.8.6;

interface ERC20Interface {
   function transfer(address to, uint tokens) external returns (bool success);
   function transferFrom(address from, address to, uint tokens) external returns (bool success);
   function balanceOf(address tokenOwner) external view returns (uint balance);
   function approve(address spender, uint tokens) external returns (bool success);
   function allowance(address tokenOwner, address spender) external view returns (uint remaining);
   function totalSupply() external view returns (uint);

   event Transfer(address indexed from, address indexed to, uint tokens);
   event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}

contract ERC20Token is ERC20Interface {
   string public name;
   string public symbol;
   uint8 public decimals;
   uint public totalSupply;
   mapping(address => uint) public balances;
   mapping(address => mapping(address => uint)) public allowed;
   
   constructor(
       string memory _name,
       string memory _symbol,
       uint8 _decimals,
       uint _totalSupply)
       public {
           name = _name;
           symbol = _symbol;
           decimals = _decimals;
           totalSupply = _totalSupply;
           balances[msg.sender] = _totalSupply;
       }
       
   function transfer(address to, uint value) public returns(bool) {
       require(balances[msg.sender] >= value);
       balances[msg.sender] -= value;
       balances[to] += value;
       emit Transfer(msg.sender, to, value);
       return true;
   }
   
   function transferFrom(address from, address to, uint value) public returns(bool) {
       uint allowance = allowed[from][msg.sender];
       require(balances[msg.sender] >= value && allowance >= value);
       allowed[from][msg.sender] -= value;
       balances[msg.sender] -= value;
       balances[to] += value;
       emit Transfer(msg.sender, to, value);
       return true;
   }
   
   function approve(address spender, uint value) public returns(bool) {
       require(spender != msg.sender);
       allowed[msg.sender][spender] = value;
       emit Approval(msg.sender, spender, value);
       return true;
   }
   
   function allowance(address owner, address spender) public view returns(uint) {
       return allowed[owner][spender];
   }
   
   function balanceOf(address owner) public view returns(uint) {
       return balances[owner];
   }
   
}

contract ERC20Token is ERC20Interface {
   string public name;
   string public symbol;
   uint8 public decimals;
   uint public override totalSupply;
   mapping(address => uint) public balances;
   mapping(address => mapping(address => uint)) public allowed;

   constructor(
       string memory _name,
       string memory _symbol,
       uint8 _decimals,
       uint _totalSupply)
   public {
       name = _name;
       symbol = _symbol;
       decimals = _decimals;
       totalSupply = _totalSupply;
       balances[msg.sender] = _totalSupply;
   }
       
   function transfer(address to, uint value) public override returns(bool) {
       require(balances[msg.sender] >= value);
       balances[msg.sender] -= value;
       balances[to] += value;
       emit Transfer(msg.sender, to, value);
       return true;
   }
   
   function transferFrom(address from, address to, uint value) public override returns(bool) {
       uint allowance = allowed[from][msg.sender];
       require(balances[msg.sender] >= value && allowance >= value);
       allowed[from][msg.sender] -= value;
       balances[msg.sender] -= value;
       balances[to] += value;
       emit Transfer(msg.sender, to, value);
       return true;
   }
   
   function approve(address spender, uint value) public override returns(bool) {
       require(spender != msg.sender);
       allowed[msg.sender][spender] = value;
       emit Approval(msg.sender, spender, value);
       return true;
   }
   
   function allowance(address owner, address spender) public override view returns(uint) {
       return allowed[owner][spender];
   }
   
   function balanceOf(address owner) public override view returns(uint) {
       return balances[owner];
   }
   
}

@Emrah 答案的實現

引用自：https://ethereum.stackexchange.com/questions/131627