英语选择
Nextyearmylittlesister___tenyearsold.
A.istobeB.isgoingtobe
C.isabouttobeD.willbe
She___lawthemomentshehasfinishedmiddleschool.
A.willbestudyingB.isabouttostudy
C.isgoingtostudyD.istostudy
分别选什么?解释一下四种将来时的区别