百度搜索输入框
class定位：
find_element_by_css_selector(".s_ipt")
id定位：
find_element_by_css_selector(".kw")
tag定位 ：
find_element_by_css_selector("input")
tag层级：
find_element_by_css_selector("span > input")
属性：
find_element_by_css_selector("[name=kw]")
组合定位：
find_element_by_css_selector("from#from > span >input#kw")
字符串:
find_element_by_css_selector("[class*s_ipt_wr]") #class 属性含wr的字符串
find_element_by_css_selector(“[class^=s]）#class以s字符串开头的
find_element_by_css_selector(”[class$=wr]")#class以wr字符串结尾的
find_element_by_css_selector("from > input:nth-chind(2)")#标签下面的第2个input的因素
find_element_by_css_selector("from > input:nth-last-child(1) ") #选择倒数第一个p元素
By定位：
#导入 from selement.webdriver.common.by import By
find_element(By.ID,"kw")
find_element(By.NAME,"WD")
find_element(By.CLASS_NAME,"s_ipt")
find_element(By.TAG_NAME,"input")
find_element(By.LINK_TEXT,"新闻")
find_element(By.PARTIAL_LINK_TEXT,"新")
find_element(By.XPATH,"//*【@class='bg s_btn']")
find_element(By.CSS_SELECTOR,"span.bg s_btn_wr>input#su")