title: How do HtmlAgilityPack extract text from html node whose class attribute appended dynamically
body: <p>Dear friends,I want to extract text <code>平均3.6 星</code> from this code segment excerpted from amazon.cn.</p>
  
  <pre><code>&lt;div class="content"&gt;&lt;ul&gt;
  &lt;li&gt;&lt;b&gt;用户评分:&lt;/b&gt;
  &lt;span class="crAvgStars" style="white-space:no-wrap;"&gt;
  &lt;span class="asinReviewsSummary" ref="dp_db_cm_cr_acr_pop_" name="B004GUSIKO"&gt;
  &lt;a&gt;
    &lt;span class="swSprite s_star_3_5 " title="平均3.6 星"&gt;
    &lt;span&gt;平均3.6 星&lt;/span&gt;
    &lt;/span&gt;
  &lt;/a&gt;
  </code></pre>
  
  <p>My question is span class tag value <code>"s_star_3_5 "</code> vary from different customer's rating level and appended dynamically. So I attempt to use <code>doc.DocumentNode.SelectSingleNode(" //span[@class='swSprite']").InnerText</code>  or <code>//span[@class='swSprite s_star_3_5 ']</code>, but the result is an error or not what my want !</p>
  
  <p>Any suggestions?</p>