covariance model

例句：

1. 1. In this study, we used a covariance model to analyze the data.
   在这项研究中，我们使用了协方差模型来分析数据。
2. 2. The covariance model is a statistical technique that helps us understand the relationship between variables.
   协方差模型是一种统计技术，它帮助我们理解变量之间的关系。
3. 3.The covariance model was used to predict the future trends of the market.
   协方差模型被用来预测市场的未来趋势。