I had had lunch at home为什么要两个had?

Daniel doesn't have lunch at home,he had lunch at school.\u6539\u9519

had \u6539\u4e3ahas

\u524d\u9762\u662f\u4e00\u822c\u73b0\u5728\u65f6\uff0c\u6240\u4ee5\u540e\u9762\u8981\u4e0e\u524d\u9762\u65f6\u6001\u4e00\u81f4


~~~~~~~~~~\uff5e\uff5e~~~~\u795d\u4f60\u8fdb\u6b65\uff0c\u5982\u5bf9\u4f60\u6709\u5e2e\u52a9\uff0c\u8bf7\u53ca\u65f6\u91c7\u7eb3~~~~~~~~~~~~~~~~

\u60a8\u597d\uff0c it seemed that he had lunch at home.(\u6539\u4e3a\u540c\u4e49\u53e5\uff09

he _seemed__ __to__ have lunch at home just now

\u4ed6\u521a\u521a\u4f3c\u4e4e\u662f\u5728\u5bb6\u91cc\u5403\u7684\u5348\u996d\u3002


seem to do \u4f3c\u4e4e\u505a\u4e86\u4ec0\u4e48\uff0c\u56fa\u5b9a\u642d\u914d

\u671b\u91c7\u7eb3O(\u2229_\u2229)O\u8c22\u8c22
\u795d\u4f60\u5b66\u4e60\u8fdb\u6b65

这是过去完成时，
sb had done sth. 第一个had就是表示过去完成时，
have lunch中have的过去分词是had,所以是
I had had lunch at home.

前面的had是助动词have的过去时，这里构成过去完成时，后面的had是动词have的完成时态。

前一个had是过去完成时的标志
而第二个had是have luch 的动词短语 因为前面是过去完成时所以要用过去分词形式 所以有两个

第一个是过去完成时的助动词
第二个是have lunch吃午饭

过去完成时态，组成是had 加上动词的过去分词，第一个是组成中的had，第二个是 have lunch中have 的过去分词 。

我已经在家吃过饭了
而不是表示我在家吃饭

扩展阅读：have a picnic ... have for lunch ... have some lunch ... do you have any ... house ... wash your hands ... do homework ... i have no idea ... what happened to you ...