可访问性不一致: 参数类型“XX”比方法“XX”的可访问性低的问题

namespace Csharp接口
{
public interface IBankAccount
{
void PayIn(decimal amount);
bool Withdraw(decimal amount);
decimal Balance
{ get; }
}

interface ITransferBankAccount : IBankAccount
{
bool TransferTo(IBankAccount destination, decimal amount);
}
}

public class CurrentAccount:ITransferBankAccount
{
private decimal balance;
public void PayIn(decimal amount)
{
balance += amount;
}

public bool Withdraw(decimal amount)
{
if (balance >= amount)
{
balance -= amount;
return true;
}
Console.WriteLine("余额不足。");
return false;
}

public decimal Balance
{
get
{
return balance;
}
}

public override string ToString()
{
return string.Format("venus账户余额：Balance = {0,6:C}", balance);
}

public bool TransferTo(IBankAccount destination, decimal amount)
{
bool result;
result = Withdraw(amount);
if (result)
{
destination.PayIn(amount);
}
return result;
}
}

public bool TransferTo(IBankAccount destination, decimal amount)
方法提示编译错误会提示：可访问性不一致: 参数类型“XX”比方法“XX”的可访问性低的问题
只需要在IBankAccount接口前面加个public修饰符即可。之前未加修饰符，一直提示错误。