has用于第三人稱單數(shù)，have用于第一、第二人稱以及第三人稱復數(shù)。關于動詞have(has)的用法。have用于第一人稱（I，we)，第二人稱(you)，及第三人稱復數(shù)（they）；has用于第三人稱單數(shù)（he，she，it)或單數(shù)名詞。

have與to一起構成情態(tài)動詞，表示“不得不”、“必須”，可用于各種時態(tài)。

I have to look after her at home.

have做助動詞與動詞的過去分詞一起構成現(xiàn)在完成時和過去完成時。

Great changes have taken place the last two years.

They said that the Arab had stolen their camel.

have用于“情態(tài)動詞＋have＋過去分詞”的結構，有推測、假設之意。

1.must＋have＋過去分詞，表示對過去時間發(fā)生的動作或存在的情況的推測，一般用于肯定句。

Her father thought that she must have met a fairy.

You must have left your bag in the theatre.

2.can(could)＋have＋過去分詞，表示對過去發(fā)生事情的“不肯定”，常用于否定句和疑問句。

He can't have been to your home, he doesn't know your address.

3.should＋have＋過去分詞，表示“某事本該早做而實際未做”，用于肯定句。

You should have been here five minutes ago.

have用于某些成語，表示固定的意思。

1.have a word(a few words)with sb.，表示和某人說一（幾）句話。

Where's Peter? I want to have a word with him.

2.had better＋不帶to的動詞不定式，表示“…最好…”。

I'd better go and look for him now.

3.have nothing(something)to do with，表示“和…無（有）”關系。

Most of questions had nothing to do with Edison's lessons.