using(file1 = new File(...))
using(file2 = new File(...))
using(file3 = new File(...))
  {
    ...bla-bla-bla...
  }

using System;

class File : IDisposable
{
    string name;

    public File(string name)
    {
        this.name = name;
    }

    public void Dispose()
    {
        Console.WriteLine(name + " disposed");
        if (name == null)
            throw new Exception();
    }

    static void Main()
    {
        try
        {
            using (var file1 = new File("file1"))
            using (var file2 = new File("file2"))
            using (var file3 = new File(null))
            {
            
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
        }
    }
}

 disposed
file2 disposed
file1 disposed
System.Exception: Exception of type 'System.Exception' was thrown.
   at File.Dispose()
   at File.Main()

using (var file1 = new File( ... ))
using (var file2 = new File( ... ))
{
  // ...
}

using System;

namespace Finally
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                try
                {
                    throw new Exception("1");
                }
                catch (Exception ex)
                {
                    throw new Exception("2", ex);
                }
                finally
                {
                    // именно в блоке finally зызывается метод Dispose
                    throw new Exception("3");
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
            }
        }
    }
}

System.Exception: 3
   at Finally.Program.Main(String[] args) in D:\Projects\Tests\Finally\Program.cs:line 22

VE>using (var file1 = new File( ... ))
VE>using (var file2 = new File( ... ))
VE>{
VE>  // ...
VE>}
VE>

try
{
  using (var file1 = new File( ... ))
  try
  {
    using (var file2 = new File( ... ))
    {
      try
      {
        // ...
      }
      catch(Exception e3)
      { ... }
    }
  } 
  catch (Exception e2)
  {  }
}
catch (Exception e1)
{  }

try
{
  File file1( ... );
  try
  {
    File file2( ... );
    try
    {
      // ...
    }
    catch ( ... ) {}
  }
  catch ( ... ) {}
}
catch ( ... ) {}

public bool ProcessJob(job j)
{
  try
  {
    using(Stream s = GetStreamForJob(j))
      WriteData(s);
    return true;
  }
  catch (Exception e)
  {
    return false;
  }
}

public bool ProcessJobStep(JobQueue q)
{
  Job j = q.Dequeue();
  j.Attempts++;
  if (!ProcessJob(j))
    q.Enqueue(); // return to queue for another attempt
}