在哪里搜索

我目前正在做一个涉及文本文件的c#小练习。所有的文本文件都是文本文件中每一行的句子。到目前为止，我能够读取文本并将其存储到字符串数组中。接下来我需要做的是搜索一个特定的词，然后写出包含搜索到的词/短语的任何句子。我只是想知道我是应该在while循环内还是在其他地方?

String filename = @"sentences.txt";

// File.OpenText allows us to read the contents of a file by establishing
// a connection to a file stream associated with the file.
StreamReader reader = File.OpenText(filename);
if (reader == null)
{
   // If we got here, we were unable to open the file.
   Console.WriteLine("reader is null");
   return;
 }
  // We can now read data from the file using ReadLine.
 Console.WriteLine();
 String line = reader.ReadLine();

  while (line != null)
  {
     Console.Write("'n{0}", line);
     // We can use String.Split to separate a line of data into fields.

     String[] lineArray = line.Split(' ');
     String sentenceStarter = lineArray[0];
     line = reader.ReadLine();

  }
  Console.Write("'n'nEnter a term to search and display all sentences containing it: ");
        string searchTerm = Console.ReadLine();
        String searchingLine = reader.ReadLine();

        while (searchingLine != null)
        {

            String[] lineArray = line.Split(' ');
            String name = lineArray[0];

            line = reader.ReadLine();
            for (int i = 0; i < lineArray.Length; i++)
            {
                if (searchTerm == lineArray[0] || searchTerm == lineArray[i])
                {
                    Console.Write("'n{0}", searchingLine.Contains(searchTerm));
                }
            }
        }