title: selenium webdriver locate the element
body: <p>i try to use selenium webdriver to locate a element:
  <a href="https://i.stack.imgur.com/pG8om.png" rel="nofollow noreferrer">i want click the "用户查询"</a></p>
  
  <p>corresponding html:
  <a href="https://i.stack.imgur.com/Vzg2t.png" rel="nofollow noreferrer">the red frame</a></p>
  
  <p>python:</p>
  
  <pre><code>&gt;&gt;&gt; driver.find_element_by_xpath("//div[@id='container']/h1[2]/a").click()
  Traceback (most recent call last):
    File "&lt;pyshell#22&gt;", line 1, in &lt;module&gt;
      driver.find_element_by_xpath("//div[@id='container']/h1[2]/a").click()
    File "D:\Python35\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 293, in find_element_by_xpath
      return self.find_element(by=By.XPATH, value=xpath)
    File "D:\Python35\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 752, in find_element
      'value': value})['value']
    File "D:\Python35\lib\site-packages\selenium\webdriver\remote\webdriver.py", line 236, in execute
      self.error_handler.check_response(response)
    File "D:\Python35\lib\site-packages\selenium\webdriver\remote\errorhandler.py", line 192, in check_response
      raise exception_class(message, screen, stacktrace)
  selenium.common.exceptions.NoSuchElementException: Message: no such element
    (Session info: chrome=52.0.2743.116)
    (Driver info: chromedriver=2.7.236900,platform=Windows NT 6.1 SP1 x86)
  </code></pre>
  
  <p>how to locate this element?</p>