underprep.低于；在 ... 下；在 ... 内；在 ... 控制下adv.在昏迷中；在 ... 下adj.下面的；从属的；少于的underseam下层

1. Time is sometimes called the fourth dimension.
   时间有时被称为第四度空间。
2. These were the so-called mainframe machines.
   它们被称为主机。