Мы работали над этой проблемой и пр

Мы работали над этой проблемой и пришли к очень интересным выводам.

Результаты (английский) 1:

We worked on this problem and came to some very interesting conclusions.

Результаты (английский) 2:

We have been working on this problem and came up with a very interesting conclusions.

Результаты (английский) 3:

We have worked on this problem and have come to a very interesting conclusions.