英语，在完成时中，如何区分使用have,has,had.

Question

如题所述

Answer 1

首先要搞清楚现在完成时和过去完成时的构成，分别是have
done
和had
done，这里面have
和had都是助动词，只表时态，没有意义，请注意下面的句子，I
have
had
dinner，第一个have是助动词，第二个had是是实意动词，吃的意思，不知道是否对你有帮助。

Answer 2

have非三单用法i
have
a
book.
has三单she
has
a
book.
had委婉或过去
you
had
better
shut
up.
he
had
a
book
yesterday.
having进行分词
she
is
having
breakfast
now.
haven不存在
haven't助动词否定用法we
haven't
met
each
other
before.