Помогите с решением, Бибилетова… стр 120, номер 13

I have just taken my puppy for a walk. (I've just taken it).I have already done my homerwork (I've already done it).I have just cleaned the parrot's cage. (I've just cleaned it).I have already joined the Zoological Society. (I've already joined it).I have already bought a good watchdog. (I've already bought it).