Question

They had already had breakfast before they arrived at the hotel. 看不懂这里的两个had

请举例说明
Most of the guest had left when he arrived at the party.
Most of the guest left when he arrived at the party.
这两句有什么差别呢? 不都是一个意思

Answer 1

They had already had breakfast before they arrived at the hotel.
这里第一个had是过去完成时, 指明时间的先后顺序
第二个had是实义动词, 在这里可以 翻译为"吃"

Most of the quest had left when he arrived at the party.
这个句子翻译为: 当他到达派对的时候, 大多数客人(已经)离开了. (离开的原因未知)
注意:主句中had后所接的动作 发生在从句的动作之前. 有先后关系.
Most of the quest left when he arrived at the party.
这个句子翻译为:当他到达派对的时候,大多数客人就离开了.(离开的原因是因为他来了)

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Answer 2

They had already had breakfast before they arrived at the hotel.
第一个had，过去完成时标志。
第二个had 是 have breakfast 吃早饭 中have的变形，因为是完成时，故用过去分词。
Most of the guest had left when he arrived at the party.
Most of the guest left when he arrived at the party.
第一句是，当他到达聚会的时候许多客人都已经离开。
第二句事，当他到打聚会的时候许多客人离开了。
意思差不多，只是第一句强调已经离开，强调作用吧！

Answer 3

（1）第一个had是助动词，过去完成时的标志（过去完成时结构：had+过去分词）
第二个是实意动词，意为“吃”，是have的过去分词。
（2）第一句过去完成时，第二句一般过去时。

Answer 4

第一句 在他到达派对前大部分客人已经离开了 强调已经发生 即强调结果
第二句 在他到达派对前大部分客人离开了 强调状态