recurrent signal

例句：

1. 1. The patient's symptoms have been recurrent in the past few years.
   病人过去几年的症状一直反复出现。
2. 2.The research has shown that recurrent infections can lead to chronic diseases.
   研究表明，反复感染可能导致慢性疾病。
3. 3. The team was able to identify patterns in the recurrent data.
   该团队能够识别出数据中的重复模式。