Я не верю, что они решили проблему

Я не верю, что они решили проблему самостоятельно. У них нет достаточно опыта. Я подозреваю, что кто-то помог им найти решение

Результаты (английский) 1:

I do not believe that they have solved the problem yourself. They do not have enough experience. I suspect that someone helped them find a solution

Результаты (английский) 2:

I do not believe that they have solved the problem on their own. They do not have enough experience. I suspect that someone has helped them to find a solution

Результаты (английский) 3:

i can't believe they solved the problem on my own. they don't have enough experience. i suspect that someone helped them to find a solution