前驱症状

例句：

1. 1. She had a fever and was experiencing some of the common symptoms of malaria.
   她发烧并出现了疟疾的一些常见症状。
2. 2. The patient showed signs of anemia, which is a precursor to more serious illnesses.
   病人出现了贫血的迹象，这是更严重疾病的先兆。
3. 3. Doctors often diagnose these symptoms as early warning signs of a more serious condition.
   医生经常将这些症状诊断为更严重疾病早期警告的标志。