为什么用has,括号内不填单词可以吗?no matter what (has) happened to you

为什么用has,括号内不填单词可以吗?no matter what (has) happened to you No matter what ( )happened to you.用have还是has what has happened to you what has happened?为什么用HAS I have no idea what has happened to him为什么是同位语从句 是what has happened to还是what has happened at you look _.What has happened to you NO matter where you are ,no matter what happened, what happened to you 和what has happened to you有什么区别 what do you suppose _______to him?为什么是has happened不是to happe What do you suppose has happened to him? Mother asked, “What has happened to you, Xiao Li?”