English homework, case pronouns?

It helps most of the time to re-write the sentence, and then figure out whether the word is working as a subject, etc. For example, the first one would be "Give the present to them.", and the last would be "She is the chairperson." The others don't really work re-written. I hope this helps! The goal as I understand it is to say what the word is doing in the sentence -- being the subject, an adjective, etc. For example, use the word "running" -- if the sentence is "Running is good exercise.", it is the subject of the sentence; if the sentence is "She is running for office.", it is not the subject, but something else. See?