he/ she/ it is.
they are是第三人称的复数形式,第三人称包含he/ she/ it. 第三人称单数的be动词用is.
第三人称单复数转换例句如下:
They are very happy.(他们非常开心)
He is very happy.(他非常开心)
She is very happy.  (她非常开心)
It's very happy.(它非常开心。)
he/ she/ it is.
they are是第三人称的复数形式,第三人称包含he/ she/ it. 第三人称单数的be动词用is.
第三人称单复数转换例句如下:
They are very happy.(他们非常开心)
He is very happy.(他非常开心)
She is very happy.  (她非常开心)
It's very happy.(它非常开心。)