1. students' chairs
2.Tom's ruler
3. Girls' pens
4. Joanna's book
5. Teacher's bag
Объяснение:
Во мн. числе ставится только апостроф без s
1.These are the students' chairs.
2.This is Tom's ruler.
3.These are girls' pens.
4.This is Joanna's book.
5.This is the teacher's bag.