请帮忙做2道选择题
9.BytheendofJune,you______hereforthreemonths.
a.willhavestudiedb.studiesc.willstudyd.havestudied
10..Yououghttogobysea,________?
a.oughtyoub.shouldn’tyouc.won’tyoud.don’tyou
请选择并讲讲为什么.谢谢了!