Here are the sentences completed with the correct possessive adjectives:

1. Sarah works in **her** office every day.
2. Richard is preparing **his** lunch.
3. I am planting some flowers in **my** garden.
4. Ann and Robert are buying a new computer for **their** son.
5. William and I are playing with **our** toys.
6. Tom is holding **his** teddy bear.
7. My father is reading the newspaper in **his** study room.