Change the long form into the short one. I have ridden a camel.

Решение:

Чтобы перейти от полной формы к краткой в Present Perfect, нужно сократить вспомогательный глагол 'have' или 'has' до 've' или 's' соответственно. При этом местоимение и сокращенный глагол пишутся слитно.

1. You have driven a car.
   Сокращаем 'have' до 've'. Получаем: You've driven a car.
2. He has flown in a pirate ship.
   Сокращаем 'has' до 's'. Получаем: He's flown in a pirate ship.
3. She has seen trapeze artists.
   Сокращаем 'has' до 's'. Получаем: She's seen trapeze artists.
4. It has found a bone.
   Сокращаем 'has' до 's'. Получаем: It's found a bone.
5. We have tried Chinese food.
   Сокращаем 'have' до 've'. Получаем: We've tried Chinese food.
6. You have travelled by boat.
   Сокращаем 'have' до 've'. Получаем: You've travelled by boat.
7. They have bought the tickets.
   Сокращаем 'have' до 've'. Получаем: They've bought the tickets.

Ответ:

1. You've driven a car.
2. He's flown in a pirate ship.
3. She's seen trapeze artists.
4. It's found a bone.
5. We've tried Chinese food.
6. You've travelled by boat.
7. They've bought the tickets.