As she tossed and turned, unable to sleep, she started going over the events that had taken place before that evening.

tossed 是动词 toss 的过去式，意思是"翻来覆去"或"辗转"，常用来形容睡不安稳时的动作。 and 是连词，在这里连接两个并列的动作"tossed"和"turned"。 turned 是动词 turn 的过去式，意思是"转身"或"翻转"。 tossed and turned 是一个固定搭配，表示"辗转反侧"，形容因焦虑或不适而无法安稳入睡的状态。