precursors [pri:'kɜ:səz]

例句:

• Infantile fears...are the precursors of many...anxieties entertained by adults
  来自E. H. Erikson
• Phenyl ( or polyphenyl ) substituted epoxides serve as excellent precursors to phenyl ( or diphenyl ) carbenes.
  某些苯代 ( 或多苯 ) 环氧乙烷是制取带苯环 ( 或二苯 ) 碳烯的极好原料.
  
• Note the presence of megakaryocytes, erythroid islands, and granulocytic precursors.
  可见巨核细胞, 红细胞岛和粒细胞前体细胞.
  
• The anomalies showed that the electromagnetic receiver can reflect earthquake precursors.
  这些异常进一步表明电磁波接收仪能反映地震前兆.
  
• The precursors of mankind ... that sounded impressive.
  来自WSJ
• Descartes was one of the precursors of the scientific revolution.
  来自NEWYORKER