<p>首先,您应该修复CSS选择器:</p>
<pre><code>.members-holder ul li.invitation-holder
</code></pre>
<p>而且,由于您需要第一个<code>li</code>,只需使用<a href="http://selenium-python.readthedocs.org/en/latest/api.html#selenium.webdriver.remote.webdriver.WebDriver.find_element_by_css_selector" rel="noreferrer">^{<cd2>} method</a>:</p>
<pre><code>driver.find_element_by_css_selector('.members-holder ul li.invitation-holder')
</code></pre>
<p>除此之外,您可能还需要e <a href="http://selenium-python.readthedocs.org/en/latest/waits.html#explicit-waits" rel="noreferrer">xplicitly wait for the element to become visible</a>:</p>
<pre><code>from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
...
element = WebDriverWait(driver, 10).until(
EC.visibility_of_element_located((By.CSS_SELECTOR, ".members-holder ul li.invitation-holder"))
)
</code></pre>
<p>如果在尝试访问元素时仍然会遇到异常,请检查元素是否在<code>iframe</code>中-如果是,请首先切换到它:</p>
<pre><code>frame = driver.find_element_by_id('frame_id')
driver.switch_to.frame(frame)
# find the element
</code></pre>