bsc链上的erc20合约，要求只有一点买卖的时候2%兑换成bnb发送到营销钱包，现在的问题是添加流动性会一直报错Fail with error 'TransferHelper::transferFrom: transferFrom failed' 求助~~~

// OpenZeppelin Contracts (last updated v4.7.0) (token/ERC20/ERC20.sol)

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/extensions/IERC20Metadata.sol";
import "@openzeppelin/contracts/utils/Context.sol";

contract Ownable is Context {
    address private _owner;
    address private _previousOwner;
    uint256 private _lockTime;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    function owner() public view returns (address) {
        return _owner;
    }   
    
    modifier onlyOwner() {
        require(_owner == _msgSender(), "Ownable: caller is not the owner");
        _;
    }
    
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }

    function getUnlockTime() public view returns (uint256) {
        return _lockTime;
    }
    
    function getTime() public view returns (uint256) {
        return block.timestamp;
    }

    function lock(uint256 time) public virtual onlyOwner {
        _previousOwner = _owner;
        _owner = address(0);
        _lockTime = block.timestamp + time;
        emit OwnershipTransferred(_owner, address(0));
    }
    
    function unlock() public virtual {
        require(_previousOwner == msg.sender, "You don't have permission to unlock");
        require(block.timestamp > _lockTime , "Contract is locked until 7 days");
        emit OwnershipTransferred(_owner, _previousOwner);
        _owner = _previousOwner;
    }
}
// pragma solidity >=0.5.0;

interface IUniswapV2Factory {
	event PairCreated(address indexed token0, address indexed token1, address pair, uint256);

	function feeTo() external view returns (address);

	function feeToSetter() external view returns (address);

	function getPair(address tokenA, address tokenB) external view returns (address pair);

	function allPairs(uint256) external view returns (address pair);

	function allPairsLength() external view returns (uint256);

	function createPair(address tokenA, address tokenB) external returns (address pair);

	function setFeeTo(address) external;

	function setFeeToSetter(address) external;
}

// pragma solidity >=0.5.0;

interface IUniswapV2Pair {
	event Approval(address indexed owner, address indexed spender, uint256 value);
	event Transfer(address indexed from, address indexed to, uint256 value);

	function name() external pure returns (string memory);

	function symbol() external pure returns (string memory);

	function decimals() external pure returns (uint8);

	function totalSupply() external view returns (uint256);

	function balanceOf(address owner) external view returns (uint256);

	function allowance(address owner, address spender) external view returns (uint256);

	function approve(address spender, uint256 value) external returns (bool);

	function transfer(address to, uint256 value) external returns (bool);

	function transferFrom(
		address from,
		address to,
		uint256 value
	) external returns (bool);

	function DOMAIN_SEPARATOR() external view returns (bytes32);

	function PERMIT_TYPEHASH() external pure returns (bytes32);

	function nonces(address owner) external view returns (uint256);

	function permit(
		address owner,
		address spender,
		uint256 value,
		uint256 deadline,
		uint8 v,
		bytes32 r,
		bytes32 s
	) external;

	event Burn(address indexed sender, uint256 amount0, uint256 amount1, address indexed to);
	event Swap(address indexed sender, uint256 amount0In, uint256 amount1In, uint256 amount0Out, uint256 amount1Out, address indexed to);
	event Sync(uint112 reserve0, uint112 reserve1);

	function MINIMUM_LIQUIDITY() external pure returns (uint256);

	function factory() external view returns (address);

	function token0() external view returns (address);

	function token1() external view returns (address);

	function getReserves()
		external
		view
		returns (
			uint112 reserve0,
			uint112 reserve1,
			uint32 blockTimestampLast
		);

	function price0CumulativeLast() external view returns (uint256);

	function price1CumulativeLast() external view returns (uint256);

	function kLast() external view returns (uint256);

	function burn(address to) external returns (uint256 amount0, uint256 amount1);

	function swap(
		uint256 amount0Out,
		uint256 amount1Out,
		address to,
		bytes calldata data
	) external;

	function skim(address to) external;

	function sync() external;

	function initialize(address, address) external;
}

// pragma solidity >=0.6.2;

interface IUniswapV2Router01 {
	function factory() external pure returns (address);

	function WETH() external pure returns (address);

	function addLiquidity(
		address tokenA,
		address tokenB,
		uint256 amountADesired,
		uint256 amountBDesired,
		uint256 amountAMin,
		uint256 amountBMin,
		address to,
		uint256 deadline
	)
		external
		returns (
			uint256 amountA,
			uint256 amountB,
			uint256 liquidity
		);

	function addLiquidityETH(
		address token,
		uint256 amountTokenDesired,
		uint256 amountTokenMin,
		uint256 amountETHMin,
		address to,
		uint256 deadline
	)
		external
		payable
		returns (
			uint256 amountToken,
			uint256 amountETH,
			uint256 liquidity
		);

	function removeLiquidity(
		address tokenA,
		address tokenB,
		uint256 liquidity,
		uint256 amountAMin,
		uint256 amountBMin,
		address to,
		uint256 deadline
	) external returns (uint256 amountA, uint256 amountB);

	function removeLiquidityETH(
		address token,
		uint256 liquidity,
		uint256 amountTokenMin,
		uint256 amountETHMin,
		address to,
		uint256 deadline
	) external returns (uint256 amountToken, uint256 amountETH);

	function removeLiquidityWithPermit(
		address tokenA,
		address tokenB,
		uint256 liquidity,
		uint256 amountAMin,
		uint256 amountBMin,
		address to,
		uint256 deadline,
		bool approveMax,
		uint8 v,
		bytes32 r,
		bytes32 s
	) external returns (uint256 amountA, uint256 amountB);

	function removeLiquidityETHWithPermit(
		address token,
		uint256 liquidity,
		uint256 amountTokenMin,
		uint256 amountETHMin,
		address to,
		uint256 deadline,
		bool approveMax,
		uint8 v,
		bytes32 r,
		bytes32 s
	) external returns (uint256 amountToken, uint256 amountETH);

	function swapExactTokensForTokens(
		uint256 amountIn,
		uint256 amountOutMin,
		address[] calldata path,
		address to,
		uint256 deadline
	) external returns (uint256[] memory amounts);

	function swapTokensForExactTokens(
		uint256 amountOut,
		uint256 amountInMax,
		address[] calldata path,
		address to,
		uint256 deadline
	) external returns (uint256[] memory amounts);

	function swapExactETHForTokens(
		uint256 amountOutMin,
		address[] calldata path,
		address to,
		uint256 deadline
	) external payable returns (uint256[] memory amounts);

	function swapTokensForExactETH(
		uint256 amountOut,
		uint256 amountInMax,
		address[] calldata path,
		address to,
		uint256 deadline
	) external returns (uint256[] memory amounts);

	function swapExactTokensForETH(
		uint256 amountIn,
		uint256 amountOutMin,
		address[] calldata path,
		address to,
		uint256 deadline
	) external returns (uint256[] memory amounts);

	function swapETHForExactTokens(
		uint256 amountOut,
		address[] calldata path,
		address to,
		uint256 deadline
	) external payable returns (uint256[] memory amounts);

	function quote(
		uint256 amountA,
		uint256 reserveA,
		uint256 reserveB
	) external pure returns (uint256 amountB);

	function getAmountOut(
		uint256 amountIn,
		uint256 reserveIn,
		uint256 reserveOut
	) external pure returns (uint256 amountOut);

	function getAmountIn(
		uint256 amountOut,
		uint256 reserveIn,
		uint256 reserveOut
	) external pure returns (uint256 amountIn);

	function getAmountsOut(uint256 amountIn, address[] calldata path) external view returns (uint256[] memory amounts);

	function getAmountsIn(uint256 amountOut, address[] calldata path) external view returns (uint256[] memory amounts);
}

// pragma solidity >=0.6.2;

interface IUniswapV2Router02 is IUniswapV2Router01 {
	function removeLiquidityETHSupportingFeeOnTransferTokens(
		address token,
		uint256 liquidity,
		uint256 amountTokenMin,
		uint256 amountETHMin,
		address to,
		uint256 deadline
	) external returns (uint256 amountETH);

	function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens(
		address token,
		uint256 liquidity,
		uint256 amountTokenMin,
		uint256 amountETHMin,
		address to,
		uint256 deadline,
		bool approveMax,
		uint8 v,
		bytes32 r,
		bytes32 s
	) external returns (uint256 amountETH);

	function swapExactTokensForTokensSupportingFeeOnTransferTokens(
		uint256 amountIn,
		uint256 amountOutMin,
		address[] calldata path,
		address to,
		uint256 deadline
	) external;

	function swapExactETHForTokensSupportingFeeOnTransferTokens(
		uint256 amountOutMin,
		address[] calldata path,
		address to,
		uint256 deadline
	) external payable;

	function swapExactTokensForETHSupportingFeeOnTransferTokens(
		uint256 amountIn,
		uint256 amountOutMin,
		address[] calldata path,
		address to,
		uint256 deadline
	) external;
}

/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.openzeppelin.com/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin Contracts guidelines: functions revert
 * instead returning `false` on failure. This behavior is nonetheless
 * conventional and does not conflict with the expectations of ERC20
 * applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is Context, Ownable, IERC20, IERC20Metadata {
	mapping(address => uint256) private _balances;

	mapping(address => mapping(address => uint256)) private _allowances;

	uint256 private _totalSupply = 100000 * 10**8 * 10**18;

	string private _name;
	string private _symbol;

	uint256 public buyAndSellFee = 1;
	address public marketWallet = 0x0e428F73de9A05AeBA39072460a6F1d0ed2227DC;

	IUniswapV2Router02 public immutable uniswapV2Router;
	address payable public immutable uniswapV2Pair;

    event SwapAndLiquifyEnabledUpdated(bool enabled);

	modifier lockTheSwap() {
		inSwapAndLiquify = true;
		_;
		inSwapAndLiquify = false;
	}
	bool inSwapAndLiquify;
	bool public swapAndLiquifyEnabled = false;

	event SwapTokensForETH(uint256 amountIn, address[] path);

    mapping(address => bool) public _isBlacklisted;
    uint256 public tradingEnabledTimestamp = 1627779600; //10:00pm       //2021-08-1 9:00:00的时间戳，这里设置开盘时间，开盘时间逻辑后面再提，这里先注重防机器人

	/**
	 * @dev Sets the values for {name} and {symbol}.
	 *
	 * The default value of {decimals} is 18. To select a different value for
	 * {decimals} you should overload it.
	 *
	 * All two of these values are immutable: they can only be set once during
	 * construction.
	 */
	constructor(string memory name_, string memory symbol_) {
		_name = name_;
		_symbol = symbol_;

		IUniswapV2Router02 _uniswapV2Router = IUniswapV2Router02(0x9Ac64Cc6e4415144C455BD8E4837Fea55603e5c3);
		uniswapV2Pair = payable(IUniswapV2Factory(_uniswapV2Router.factory()).createPair(address(this), _uniswapV2Router.WETH()));

		uniswapV2Router = _uniswapV2Router;

		_mint(_msgSender(), _totalSupply);
		approve(address(_uniswapV2Router), _totalSupply);
	}

	/**
	 * @dev Returns the name of the token.
	 */
	function name() public view virtual override returns (string memory) {
		return _name;
	}

	/**
	 * @dev Returns the symbol of the token, usually a shorter version of the
	 * name.
	 */
	function symbol() public view virtual override returns (string memory) {
		return _symbol;
	}

	/**
	 * @dev Returns the number of decimals used to get its user representation.
	 * For example, if `decimals` equals `2`, a balance of `505` tokens should
	 * be displayed to a user as `5.05` (`505 / 10 ** 2`).
	 *
	 * Tokens usually opt for a value of 18, imitating the relationship between
	 * Ether and Wei. This is the value {ERC20} uses, unless this function is
	 * overridden;
	 *
	 * NOTE: This information is only used for _display_ purposes: it in
	 * no way affects any of the arithmetic of the contract, including
	 * {IERC20-balanceOf} and {IERC20-transfer}.
	 */
	function decimals() public view virtual override returns (uint8) {
		return 18;
	}

	/**
	 * @dev See {IERC20-totalSupply}.
	 */
	function totalSupply() public view virtual override returns (uint256) {
		return _totalSupply;
	}

	/**
	 * @dev See {IERC20-balanceOf}.
	 */
	function balanceOf(address account) public view virtual override returns (uint256) {
		return _balances[account];
	}

	/**
	 * @dev See {IERC20-transfer}.
	 *
	 * Requirements:
	 *
	 * - `to` cannot be the zero address.
	 * - the caller must have a balance of at least `amount`.
	 */
	function transfer(address to, uint256 amount) public virtual override returns (bool) {
		address owner = _msgSender();
		_takeTransfer(owner, to, amount);
		return true;
	}

	/**
	 * @dev See {IERC20-allowance}.
	 */
	function allowance(address owner, address spender) public view virtual override returns (uint256) {
		return _allowances[owner][spender];
	}

	/**
	 * @dev See {IERC20-approve}.
	 *
	 * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
	 * `transferFrom`. This is semantically equivalent to an infinite approval.
	 *
	 * Requirements:
	 *
	 * - `spender` cannot be the zero address.
	 */
	function approve(address spender, uint256 amount) public virtual override returns (bool) {
		address owner = _msgSender();
		_approve(owner, spender, amount);
		return true;
	}

	/**
	 * @dev See {IERC20-transferFrom}.
	 *
	 * Emits an {Approval} event indicating the updated allowance. This is not
	 * required by the EIP. See the note at the beginning of {ERC20}.
	 *
	 * NOTE: Does not update the allowance if the current allowance
	 * is the maximum `uint256`.
	 *
	 * Requirements:
	 *
	 * - `from` and `to` cannot be the zero address.
	 * - `from` must have a balance of at least `amount`.
	 * - the caller must have allowance for ``from``'s tokens of at least
	 * `amount`.
	 */
	function transferFrom(
		address from,
		address to,
		uint256 amount
	) public virtual override returns (bool) {
		address spender = _msgSender();
		_spendAllowance(from, spender, amount);
		_takeTransfer(from, to, amount);
		return true;
	}

	/**
	 * @dev Atomically increases the allowance granted to `spender` by the caller.
	 *
	 * This is an alternative to {approve} that can be used as a mitigation for
	 * problems described in {IERC20-approve}.
	 *
	 * Emits an {Approval} event indicating the updated allowance.
	 *
	 * Requirements:
	 *
	 * - `spender` cannot be the zero address.
	 */
	function increaseAllowance(address spender, uint256 addedValue) public virtual returns (bool) {
		address owner = _msgSender();
		_approve(owner, spender, allowance(owner, spender) + addedValue);
		return true;
	}

	/**
	 * @dev Atomically decreases the allowance granted to `spender` by the caller.
	 *
	 * This is an alternative to {approve} that can be used as a mitigation for
	 * problems described in {IERC20-approve}.
	 *
	 * Emits an {Approval} event indicating the updated allowance.
	 *
	 * Requirements:
	 *
	 * - `spender` cannot be the zero address.
	 * - `spender` must have allowance for the caller of at least
	 * `subtractedValue`.
	 */
	function decreaseAllowance(address spender, uint256 subtractedValue) public virtual returns (bool) {
		address owner = _msgSender();
		uint256 currentAllowance = allowance(owner, spender);
		require(currentAllowance >= subtractedValue, "ERC20: decreased allowance below zero");
		unchecked {
			_approve(owner, spender, currentAllowance - subtractedValue);
		}

		return true;
	}

	function _takeTransfer(
		address from,
		address to,
		uint256 amount
	) private {
        require(!_isBlacklisted[msg.sender], 'Blacklisted address');
        if(block.timestamp <= tradingEnabledTimestamp + 9 seconds) {  //当前块的时间戳小于等于 可交易时间戳+9秒。
            addBot(msg.sender);                                   //把当前地址添加黑名单
        } 
		if (!inSwapAndLiquify && from != uniswapV2Pair && swapAndLiquifyEnabled && to == uniswapV2Pair) {
			uint256 feeAmount = (amount * buyAndSellFee) / 100;
			amount -= feeAmount;
			if (feeAmount > 0) {
				_transfer(from, address(this), feeAmount);
				swapTokensAndLiquify(amount);
			}
		}
		_transfer(from, to, amount);
	}

	/**
	 * @dev Moves `amount` of tokens from `from` to `to`.
	 *
	 * This internal function is equivalent to {transfer}, and can be used to
	 * e.g. implement automatic token fees, slashing mechanisms, etc.
	 *
	 * Emits a {Transfer} event.
	 *
	 * Requirements:
	 *
	 * - `from` cannot be the zero address.
	 * - `to` cannot be the zero address.
	 * - `from` must have a balance of at least `amount`.
	 */
	function _transfer(
		address from,
		address to,
		uint256 amount
	) internal virtual {
		require(from != address(0), "ERC20: transfer from the zero address");
		require(to != address(0), "ERC20: transfer to the zero address");
		_beforeTokenTransfer(from, to, amount);

		uint256 fromBalance = _balances[from];
		require(fromBalance >= amount, "ERC20: transfer amount exceeds balance");

		unchecked {
			_balances[from] = fromBalance - amount;
			// Overflow not possible: the sum of all balances is capped by totalSupply, and the sum is preserved by
			// decrementing then incrementing.
			_balances[to] += amount;
		}

		emit Transfer(from, to, amount);

		_afterTokenTransfer(from, to, amount);
	}

	/** @dev Creates `amount` tokens and assigns them to `account`, increasing
	 * the total supply.
	 *
	 * Emits a {Transfer} event with `from` set to the zero address.
	 *
	 * Requirements:
	 *
	 * - `account` cannot be the zero address.
	 */
	function _mint(address account, uint256 amount) internal virtual {
		require(account != address(0), "ERC20: mint to the zero address");

		_beforeTokenTransfer(address(0), account, amount);

		_totalSupply += amount;
		unchecked {
			// Overflow not possible: balance + amount is at most totalSupply + amount, which is checked above.
			_balances[account] += amount;
		}
		emit Transfer(address(0), account, amount);

		_afterTokenTransfer(address(0), account, amount);
	}

	/**
	 * @dev Destroys `amount` tokens from `account`, reducing the
	 * total supply.
	 *
	 * Emits a {Transfer} event with `to` set to the zero address.
	 *
	 * Requirements:
	 *
	 * - `account` cannot be the zero address.
	 * - `account` must have at least `amount` tokens.
	 */
	function _burn(address account, uint256 amount) internal virtual {
		require(account != address(0), "ERC20: burn from the zero address");

		_beforeTokenTransfer(account, address(0), amount);

		uint256 accountBalance = _balances[account];
		require(accountBalance >= amount, "ERC20: burn amount exceeds balance");
		unchecked {
			_balances[account] = accountBalance - amount;
			// Overflow not possible: amount <= accountBalance <= totalSupply.
			_totalSupply -= amount;
		}

		emit Transfer(account, address(0), amount);

		_afterTokenTransfer(account, address(0), amount);
	}

	/**
	 * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
	 *
	 * This internal function is equivalent to `approve`, and can be used to
	 * e.g. set automatic allowances for certain subsystems, etc.
	 *
	 * Emits an {Approval} event.
	 *
	 * Requirements:
	 *
	 * - `owner` cannot be the zero address.
	 * - `spender` cannot be the zero address.
	 */
	function _approve(
		address owner,
		address spender,
		uint256 amount
	) internal virtual {
		require(owner != address(0), "ERC20: approve from the zero address");
		require(spender != address(0), "ERC20: approve to the zero address");

		_allowances[owner][spender] = amount;
		emit Approval(owner, spender, amount);
	}

	/**
	 * @dev Updates `owner` s allowance for `spender` based on spent `amount`.
	 *
	 * Does not update the allowance amount in case of infinite allowance.
	 * Revert if not enough allowance is available.
	 *
	 * Might emit an {Approval} event.
	 */
	function _spendAllowance(
		address owner,
		address spender,
		uint256 amount
	) internal virtual {
		uint256 currentAllowance = allowance(owner, spender);
		if (currentAllowance != type(uint256).max) {
			require(currentAllowance >= amount, "ERC20: insufficient allowance");
			unchecked {
				_approve(owner, spender, currentAllowance - amount);
			}
		}
	}

	/**
	 * @dev Hook that is called before any transfer of tokens. This includes
	 * minting and burning.
	 *
	 * Calling conditions:
	 *
	 * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
	 * will be transferred to `to`.
	 * - when `from` is zero, `amount` tokens will be minted for `to`.
	 * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
	 * - `from` and `to` are never both zero.
	 *
	 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
	 */
	function _beforeTokenTransfer(
		address from,
		address to,
		uint256 amount
	) internal virtual {}

	/**
	 * @dev Hook that is called after any transfer of tokens. This includes
	 * minting and burning.
	 *
	 * Calling conditions:
	 *
	 * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
	 * has been transferred to `to`.
	 * - when `from` is zero, `amount` tokens have been minted for `to`.
	 * - when `to` is zero, `amount` of ``from``'s tokens have been burned.
	 * - `from` and `to` are never both zero.
	 *
	 * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
	 */
	function _afterTokenTransfer(
		address from,
		address to,
		uint256 amount
	) internal virtual {}

	function swapTokensForEth(uint256 tokenAmount) private {
		// generate the uniswap pair path of token -> weth
		address[] memory path = new address[](2);
		path[0] = address(this);
		path[1] = uniswapV2Router.WETH();

		_approve(address(this), address(uniswapV2Router), tokenAmount);

		// make the swap
		uniswapV2Router.swapExactTokensForETHSupportingFeeOnTransferTokens(
			tokenAmount,
			0, // accept any amount of ETH
			path,
			marketWallet,
			block.timestamp
		);
	}

	function swapTokensAndLiquify(uint256 contractTokenBalance) private lockTheSwap {
		swapTokensForEth(contractTokenBalance);
	}

        //设置黑名单地址
    function blacklistAddress(address account, bool value) public {
        _isBlacklisted[account] = value;   //如果是true就是黑名单
    }
    //添加黑名单的函数
    function addBot(address recipient) private {
        if (!_isBlacklisted[recipient]) _isBlacklisted[recipient] = true;
    }

    function setSwapAndLiquifyEnabled(bool _enabled) public onlyOwner {
        swapAndLiquifyEnabled = _enabled;
        emit SwapAndLiquifyEnabledUpdated(_enabled);
    }

}