Question

15．当他到达学校时，他认识到他把背包忘在家了．（had left）
When he arrived at school，he realized that he had left his backpack at home．

Answer 1

分析 根据句意，该句用以when引导的时间状语从句表达．

解答 答案：When he arrived at school，he realized that he had left his backpack at home；该题考查学生的英语表达能力；根据句意，该句用以when引导的时间状语从句表达，从句和主句用一般过去时表达，主句中的宾语从句"发生在过去的过去"，用过去完成时，过去完成时的基本结构结构：had+动词的过去分词构成；到达，arrive at；故填When he arrived at school，he realised that he had left his backpack at home．

点评 根据句意，确定好句子的时态是解题的关键；还要识记常用短语，运用单词和短语的适当形式作答，所以要积累掌握词汇，识记常用短语，还要熟练掌握句型．