例句與造句

1. using a multi-stage cluster sampling design, each of the three cities selected 21 secondary schools with a probability proportional to size to participate in the study
   運(yùn)用多階段集群抽樣方法，各參與城市的所有普通中學(xué)，按學(xué)校學(xué)生人數(shù)比例作為學(xué)校抽樣機(jī)率，每地區(qū)抽出21間學(xué)校。
2. It's difficult to find probability proportional to size in a sentence. 用probability proportional to size造句挺難的