为什么有些句子的动词要加ing ,s,还有 怎样问答Do you have...Does he/she...

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句子中的动词加ing,通常表示句子的时态是现在进行时,如
He is playing guitar.
They're singing.
加s,则通常表示的时态是一般现在时或者第三人称单数,如
She likes dancing.中的like就加了s,因为she是“她”,表示一个人,后面的谓语动词要用单数.
Mike goes to school on foot.
遇到Do you have... Does he/she...的句子,回答时根据具体情况.如：
Do you have a camera?
Yes,I do./No,I don't.
Does she like listen to music?
Yes,she does./No, she doesn't.