Tony was shocked. He couldn't believe what (happen).​

Конкретного задания не вижу, просто раскрыл скобки:

Tony was shocked. He couldn't believe what happened.

Tony was shocked. He couldn't believe what had happened.

Здесь мы используем Past perfect, так как говорим о действии,которое произошло раньше,чем ещё что-то в

В данной ситуации: Он был шокирован и не мог поверить(PS) в то,что произошло еще раньше,то есть в то есть PP

Hello, in the afternoon I usually do business, and rest. In the morning I will get up and do the lessons that are being asked. After school, I wash my face and have breakfast, after which I go to school. At school, we are engaged, and perform the task in notebooks. After school, I usually go to my favorite store. I rest at home or after school. In the evening, my family and I usually watch TV shows. this is how my day goes.

- Cool!