what has happened to the earth in the last ten years 为什么是完成时呢?讲细一点~

是what has happened to还是what has happened at快,还有后面加什么! what happened to you 和what has happened to you有什么区别 I wanted to know_to him.为什么填what happened而不是what has happened? --What _ to them?--they appeared__in the accident.A.has happened to,be injured B.happened ,to have been injuredC.has happened to ,be injured D.happened ,injured No matter what ( )happened to you.用have还是has what has happened to you这不是被动语态吗? What on earth has happened to make you so upset? what has happened to our weather?如题~ What has happened to your country什么意思 what happened to 和what happened what's happened to them 's=has?为什么不是have 是them 为什么不是what've happened to them What Happened to Us Dear,what happened to what happened to she what happened to him? what happened to what happened to the He asked,What has happened to you?变为间接引语该怎么变是He asked what had happened to me.还是He asked what I had happened .