Sam ( )here half an hour ago括号中应填什么?为什么?

Sam ( )here half an hour ago括号中应填什么?为什么? took Sam half an hour to send these qictures by e-mail.Sam＿half an hour ＿ these pictures by e-mail.保持原句意思不变 they will come here in half an hour.(对in half an hour提问) ( ) ( ) ( )your house from here?Half an hour's walk. they were here about half an hour ago They left here half an hour ago.(同意句转换) He was here().A.half an hour before B.half hour ago C.half an hour ago Half an the bus arrive here half an hour ago . lt is here now 的同义句是什么? The bus arrived here haIf an hour ago 改为同义句 The bus（ ）（ ）here( )half an hour It takes me more than half an hour to get here,(对more than half an hour to get here提问） He will be here in half an hour.为什么will后用bHe will be here in half an hour.为什么will后用be It is only__walk,so you can get here on foot.选项A.HALF AN HOUR B.HALF AN HOUR′SC.HALF AN HOURS D.HALF AN HOURS′ The market isn't far from here .It's only _____ bicycle ride.A.half an hour's B.half an hours' C.half an hour D.one hour and a half It`s about__A__ from here.A.a half-hour`s drive B.half-an-hour drive C.a half-an-hour drive D.half an hors` drive 为什么选A It is half an hour is walk from here to the bus station The bus arrived here half an hour ago.改为同义句 It is about half an hour since he came here.请问一下后面为什么是过去式?