名词 sterol:

1. any of a group of natural steroid alcohols derived from plants or animals; they are waxy insoluble substances

STEabbr.专用测试设备(=Special Test Equipment)abbr.适合性试验的鉴定(=Suitability Test Evaluation)Stefl施特夫尔

1. Insects need an external source of sterols.
   昆虫需要外界来源的固醇类。