in a minute's time 单数形式minute为什么要加's

in a minute's time 单数形式minute为什么要加's minute能不能加s 如：minute’s ,minute'.. wait a minute e后面要加s吗 Just a minute It`s a twenty-minute-walk or a twenty-minute's walk But it's going to be fine in a minute. It's about ten()walk.A.minute's B.minute C.minutes' D.minute It’s going to be fine in a minute的问句是什么!画线部分是：in a minute.就划 minute's可能吗? five minute's walk / five-minute walk A:It's one minute to eleven.