css_selector定位，比xpath速度快，语法简洁

driver.get("http://www.baidu.com")
#根据ID来定位
driver.find_element_by_css_selector('#kw').send_keys('selenium')
driver.find_element_by_id('su').click()

#根据class来定位
driver.find_element_by_css_selector('.s_ipt').send_keys('selenium')
driver.find_element_by_id('su').click()

#根据属性来定位
driver.find_element_by_css_selector('[autocomplete="off"]').send_keys('python')