A. We didn't use to have a colorful TV, but we do now.
Corrected: We didn't use to have a color TV, but we do now. OR We used not to have a color TV, but we do now.
Explanation: "Colorful" should be "color" when referring to a color television set. Also, the negative form of "used to" can be either "didn't use to" or "used not to".

B. When my baby sister is younger, she didn't use to eat pizza.
Corrected: When my baby sister was younger, she didn't use to eat pizza.
Explanation: The time clause should be in the past tense ("was") to match the main clause ("didn't use to").

C. It's about 500 meters at my house to school.
Corrected: It's about 500 meters from my house to school.
Explanation: The correct preposition is "from," not "at," when indicating the distance between two locations.

B. On my way home get school, I sometimes see a train pass by.
Corrected: On my way home from school, I sometimes see a train pass by.
Explanation: The preposition "from" is needed to show the starting point of the journey.

C. Did he use to crying all night when his father died.
Corrected: Did he use to cry all night when his father died?
Explanation: After "use to," the base form of the verb (cry) should be used, not the gerund (-ing form).