Has she visited China before?为什么用现在完成时?

Has she visited China before?为什么用现在完成时? She's visited China before 现在完成时划线提问Jane has visited the UK before 划线 the UK-------- -- She has visited many countries中为什么会有has 句型转换1.She's visited China before.（改为一般疑问句）_____she _____ Chi 英语；visited China before 什莫意思? she has emptied the basket this morning为什么不是现在完成时? 为什么现在完成时可以用before,ago却不行? She has not visited Beijing.N___ has she. ever,Beijing,before ,visited,has,Tom 连词成句 i don't know if she has turned off the light.为什么要使用现在完成时 before现在完成时