They divided the subjects into four groups -- light, moderate and heavy drinkers and abstainers -- and did a 20-year follow-up analysis from the study baseline.

这些试验者人被划分为四个小组——微量饮酒者，适度饮酒者及酗酒者——并进行了自这项研究伊始为期20年的跟踪调查分析。