Привет! Давай вместе исправим ошибки в предложениях.
Elephants are stronger that horses. Правильно: Elephants are stronger than horses. (than вместо that)
Have you ever be to Paris? Правильно: Have you ever been to Paris? (двойное участие been вместо be)
You should to do your homework before you go out. Правильно: You should do your homework before you go out. (без to после should)
I think dogs are more friendlier than cats. Правильно: I think dogs are friendlier than cats. (более дружелюбные - friendlier без more)
My friend going to help his father this summer. Правильно: My friend is going to help his father this summer. (is going to)
He have to wear a uniform at my school. Правильно: He has to wear a uniform at my school. (has вместо have)
This is the most big city of my country. Правильно: This is the biggest city in my country. (правильное превосходное: biggest)
I'm going visit my grandparents on August. Правильно: I'm going to visit my grandparents in August. (to перед visit и in August вместо on August)
Надеюсь, это поможет! Удачи с учебой! 😊