Active previous course的用法和样例：
- Keywords Tranquilizer;Mountain scopolamine hyoscine;Active previous course;Application;
- Can you look at my records to see if my previous courses qualify me to take a more advanced psychology course?
- Undelete and activate previously deleted text ads.
- Based on the traffic forecasting and the time interval during which each node needed to be active previously, TB-MAC could compute the sleep/wakeup schedule.