text_1: 我们 利用 Lan 和 DeMets 提出 的 a 消耗 函数 , 结合 O ' Brien 和 Fleming 成组 序贯界值 确定 了 疗效 监测 指南 20 , 21 .
  
text_2: the guideline for monitoring efficacy was determined by an alpha @-@ spending function , proposed by Lan and DeMets , and harmonizes with the O 'Brien and Fleming group @-@ sequential boundary.20,21
  