He wondered what had happened.是什么意思？

He wondered what had happened.

他想知道发生了什么事。

he

pron. 他，它，一个人；n. 雄性动物；

例句
Logic had prevailed and he had abandoned the idea.
最终理智占了上风，他打消了那个念头。

wondered

vt. 对…感到好奇（wonder的过去式与过去分词形式）；

例句
I wondered why he had gone through the elaborate charade...
我不明白，他为什么要大费周章，装腔作势。

what

pron. （用以询问某人或某事物的词）什么，多少，…的事物；adj. …的（事物或人）；adv. （用于感叹句中）；int. （用以表示不相信或惊奇），（用以表示未听清楚对方说的话）；

例句
How big is the abyss between what you think you are and what you actually are?
你对自己的认识和真实的你之间差别到底有多大？

had

v. 有（ have的过去式和过去分词 ），（亲属关系中）接受，拿，买到；

例句
He claimed that his parents had abandoned him...
他声称父母遗弃了他。

happened

v. 发生（ happen的过去式和过去分词 ），出现，碰巧；

例句
He gave a detailed account of what happened on the fateful night...
他详细描述了那个灾难性夜晚所发生的事。