Object forms of personal pronouns - Exercise

Which bject form of the personal pronoun can substitute the underlined phrase in the sentence?

1) The teacher always gives the students homework. me them you
2) I am reading the book to my little sister. her us him
3) The boys are riding their bikes. it them her
4) My father is writing a letter to John. me her him
5) I don't know the answer. she her it
6) Sally is going to Anne. her him me
7) Open the window, please. it them us
8) Can you tell the people the way to the airport, please? you them us
9) The books are for Peter. him her you
10) Can you help my sister and me, please? her me us