Replace and append using linq

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C#

LINQ

Hi guys I want to use replace in a single line of code using Linq

my ListBoxItem contains this words

MEA+AAE+VGM+KGM:16795'
FTX+AAI+++?CONTAINERSTOBESTOWEDAWAYFROMHEATANDTOBESTOREDUNDERDECK?'
TDT+1++3++688888:172:87+++:172:87'

and I want to replace the character '?' and place the new lines
in File.WriteAllLines(filePath, newLines);

What you see on the below code is a method to delete the whole selected line

I want to change that to a method that can replace the question mark sign'?'
using linq

string[] lines = File.ReadAllLines(filePath);
foreach (string line in lines) // Read all line from the text file  
{
   oListBox.Items.Add(line);
}
foreach (var listBoxItem in oListBox.Items)
{
  if (listBoxItem.ToString().Contains("?"))
  {
     string word = listBoxItem.ToString();
     var oldLines = File.ReadAllLines(filePath);
     var newLines = oldLines.Where(line => !line.Contains(word));//delete the selected line  
     
     File.WriteAllLines(filePath, newLines);
     FileStream oFileStream = new FileStream(filePath, FileMode.Append);
     oFileStream.Close();
   }
}

What I have tried:

I still trying to experiment different code using linq