have,has,had只有作助动词时才会弱读，当它们作实义动词时要重读的。如：

I have a sister.

have有实际意义，是实义动词，在它后面通常出现一个名词。

I have seen the movie before.

have没有实际意义，是助动词，它和动词过去分词搭配出现。

have

强读式：/hæv/

不在句首时，弱读式/əv/

What have you done?

在句首时，弱读式/həv/

Have you eaten yet?

has

强读式：/hæz/

不在句首时，弱读式/əz/

He has been training.

在句首时，弱读式/həz/

Has he done it before?

had

强读式：/hæd/

不在句首时，弱读式/əd/

I had been working back then.

在句首时，弱读式/həd/

Had he always been kind?