Je ne comprends pas l'exercice si quelqu'un pourrait m'aider svp

Posez une question pour avoir l'information qui manque. exemple: They decided to (?). What did they decide to do?

a. He bought (?) at the shops yesterday.
b. He saw (?), who was shopping too.
c. I'm thinking of going to (?) tomorrow, if I have the time.
d. Mary says she will write (?) to the company to ask them to stop manufacturing abroad.
e. (?) says she will sign an online petition.​