Zimmerman ( 1994 ) finds that that 3 hours a week of explicit vocabulary instruction plus some self-selected reading were more effective than reading alone; and Jan H. Hulstijin ( 1997 ) introduces the keyword method and how to practice it in L2 instruction. Zimmerman发现,三周直接明了的词汇教学加之于自选阅读(SSR)比单独阅读更为有效:而JanH.Hulstiiin则介绍了关键词的方法以及如何在二语教学中实践。