Some preset the system time on their computers to view the blackout, with help from online instructions.
一些人预先设定了电脑的系统时间，在在线说明的帮助下看黑屏。
2
Because of the dual-orifice design, there is a preset controlled pressure differential for the secondary steam system, while maximum pressure differential is available to discharge the condensate.
A sleep function allows the drives to be cycled off when the system demand drops below a preset level, and restarted automatically when the demand increases.