title: using data.table::fread to import data but get NA columns
body: <p>I have a <code>.csv</code> data, including 39635 obs. of 11 variables.<br>
  However, I use <code>data.table::fread()</code> to import my data and get 13 variables.<br>
  All cells under 12 and 13 column are <code>NA</code>.<br>
  How can I control it to import correctly?  </p>
  
  <pre><code>dt &lt;- data.table::fread("data.csv", header = TRUE, strip.white = TRUE)
  </code></pre>
  
  <p>I know I can use <code>select</code>: Vector of column names or numbers to keep, drop the rest and <code>drop</code>: Vector of column names or numbers to drop, keep the rest.<br>
  Is there other ways to solve this?  </p>
  
  <p><strong>UPDATE</strong><br>
  my data:  </p>
  
  <pre><code>col1 col2 col3 .....  col11
  A    123  ABC  .....  123456
  B    234  XYZ  .....  987654
  </code></pre>
  
  <p>After importing:  </p>
  
  <pre><code>col1 col2 col3 .....  col11   V1  V2
  A    123  ABC  .....  123456  NA  NA
  B    234  XYZ  .....  987654  NA  NA
  </code></pre>
  
  <p>where <code>NA</code> is not character. it means missing value.</p>