title: remove a string in list
body: <p>I have a nested list (l1) containing several lists of sentences (i) and I want to remove a particular string from the second element in (i) when the split() method is applied to it. However it seems that only half of them are removed and the rest remain. </p>
  
  <p>This is what I have tried:</p>
  
  <pre><code>for i in l1:
      for j in i[1].split():
          if j == 'a':
              i[1].split().remove(j)
  </code></pre>
  
  <p>I have also tried to replace (j) with an empty string, but it wasn't helpful either.</p>
  
  <p>example input: [[string1, This is a book], [string2, He is a tall man], ,,,]</p>
  
  <p>example output: 
  This is book, He is tall man</p>