half a day 为何不说half day.类比half apple

half a day 为何不说half day.类比half apple half a day 为何不说a half day half of students为啥不说a half of half a day=a half day,那为什么half a dozen 却没有a half dozen 这种说法? he often___(relax) half a day half a a half half a a half half Half half they spent half a day planting trees的同义句?they spent half a day planting treesit ___them half a day ___ ___the trees? For a day and a half last spring 翻译... 改错 He stayed here one and a half day a half apples还是a half apple a half与half a的区别 a half mile 还是half a mile