是what happen...还是what happens...?

是what happen...还是what happens...? What happen还是What is happen? what if 的完全形式是 what would happen 还是what will happen what would happen if .可不可以是what will happen if . whatll happen 和whatll they do分别是什么式,是过去式还是将来式? 是How could this happen?还是What could this happen?为什么呢?语法结构上如何分析啊？ What happen what happen what's happen的's代表什么到底是has还是is？还有我在书是上看的就是what's happen what happen to you还是what happened to you? what happen to you?还是what happens to you? what happen to sb 还是 what happened to sb What's happen?是词组吗 i don't know what happen ,后面的名词性从句what是代主语还是宾语. What happen ( )your bike yesterday?用to还是 in ,解释一下. I can't go to school today,Mum?Why_______,dearA,Wha's happed to ypu B.What did you happen C.What was wrong with you D.What's the matter with you No one knows what （happen）in 100 years in 100 years是指过去还是现在 They never knew what( )to the world in a hundred years.是would happen 还是would be happened?