请教几道英语题,O(∩_∩)O谢谢
1.His grandmother ___ for thirty years.
A.died B.had died C.has been dead D.has died
2.Collecting dolls as a hobby ___ increasingly popular during the past fifty years.
A.became B.has become C.was D.has been
3.I ___a college student for more than a year.
A.became B.have bacome C.was D.have been