My sister has two children, so she is busy with them in the mornings. I leave for work at 7:00am. My sister never goes straight to work.
the subject : my sister
the predicat : has( agreement thirt singular person)
the second sentence
the subject is the pronoun she
the predicat is the verbe be
the last sentense
the subject : my sister
the predicat is the verb go ( agreement thirt singular person)