Her thoughts were interrupted by Ben, who asked if she wanted to go for a walk with him.

interrupted 是动词 interrupt 的过去分词形式，在句中表示被动。interrupt 由前缀 inter-（表示"在...之间"）和词根 rupt（来自拉丁语 rumpere，意为"打破"）组成，字面意思是"在中间打断"，引申为"打断、中断"的意思。interrupted 在这里表示"被打断"的状态。