1. The Elena-sleeps-with-her-professor plotline, dropped at the beginning of the second season, served mostly to trivialize Elena's dedication to her studies.

2. A Cliffhanger (KLIF-hang-ur) is the abrupt ending of a plotline that leaves major elements of the story unresolved until the next installment of the work.It can be something as simple as an interrupted bit of dialogue or something as drastic as a character death