series triggering

例句：

1. 1. The book has a series of chapters that are easy to follow.
   这本书有一系列章节，容易跟随。
2. 2. They have a series of events planned for the weekend.
   他们计划了一系列周末的活动。
3. 3. The series of photos document the journey from start to finish.
   这一系列的照片记录了从开始到结束的旅程。