//input[@name='log']
//input[@id='user_login']
//a[@title='Powered by WordPress']
//input[@class='input'][@name='log']
//input[@class='input' OR @name='log']
//input[@class='input' and @name='log']
//a[@id='id1'][@name='namevalue1']
//a[contains(@href,'')]
//img[contains(@src,'')]
//div[contains(@id,'')]
//input[contains(@name,'nickname')] #这条自己测试可行，后面可以加@爬取
//id[start-with(@id,'')]
//a[start-with(@href='')]
//img[start-with(@src='')]
//*[text()=''] #好像不能模糊搜索
//following::