Open the brackets and put the verbs in Passive Voice:
Marry Poppins______(to create) by the Australian writer P.L. Travers. In 1964, it _______(to make) into a popular Walt Disney film. The main role ________ ( to play) by Julie Andrews.

Mary Poppins was created by the Australian writer P.L. Travers. In 1964, it was made into a popular Walt Disney film. The main role was played by Julie Andrews.

Passive voice is formed by using the auxiliary verb "to be" in the appropriate tense, followed by the past participle of the main verb. In this case, "create" becomes "created" in the past tense, "make" becomes "made" in the past tense, and "play" becomes "played" in the past participle form.