Not until the train pulled into the station --- that the sui

选C.过去完成时态.因为这是一个典型的not until置前的条件式强调句.
not其实是对主句的谓语动词的否定,而且是在条件从句发生之前就已经存在的事实,所以主句要用过去完成时态.
这种结构中的主句只能用陈述句,所以其它的都不对.
再问： 谢谢额  可不可以帮我划分一下句子成分  我不太会
再答： Not until the train pulled into the station he had found that the suitcase was gone. until the train pulled into the station 条件从句，until为条件引导词，后面为时间条件状语 he had found that the suitcase was gone主句，主语he，谓语had found，宾语为that从句 that the suitcase was gone宾语从句，that为宾语引导词，the suitcase为从句主语，与was gone的被动式非谓语动词构成【逻辑主语+分词】的独立结构。