Unless she had had an alarm clock, she would havemissed the train.（事实：她没有闹钟）中两个had是什么意思?
问题描述：
Unless she had had an alarm clock, she would havemissed the train.（事实：她没有闹钟）
中两个had是什么意思?
答
had had:第一个had是过去完成时的助动词,第二个had是have的过去分词.它们一起构成过去完成时.
条件句中用过去完成时,是对过去情况的虚拟语气,表示与过去事实相反的假设.
Unless she had had an alarm clock, she would have missed the train.
=If she had not had an alarm clock, she would have missed the train.
句意:如果她没有闹钟,她就已经错过了那列火车.
事实是:她有闹钟,所以她没有错过火车.
答
虚拟语气结构对过去的虚拟：had +动词过去分词
所以第一个had是助动词第二个是过去分词