一、时态讲解:现在完成时
(1)构成:现在完成时由助动词have + 过去分词构成,助动词have 有人称和数的变化。第三人称单数用has,其余用have.
现在完成时的否定式直接在助动词后面加上not、疑问式是把助动词提到主语之前。以study 为例,其否定式、疑问式和简单回答形式如下:
否定式
疑问式
I have not (haven’t) studied….
Have I studied…?
You have not (haven’t) studied….
Have you studied…?
He has not (hasn’t) studied….
Has he studied…?
否定疑问式
简单回答(肯定/否定)
Have I not (Haven’t I) studied…?
Yes, you have. No, you haven’t.
Have you not (Haven’t you) studied…?
Yes, I have. No, I haven’t.
Has he not (Hasn’t he) studied…?
Yes, he ha