В тот день у нас было много работы,

В тот день у нас было много работы, так как вечером мы уезжали.

Результаты (английский) 1:

On that day, we had a lot of work, because we left in the evening.

Результаты (английский) 2:

On that day, we had a lot of work, as we were leaving in the evening.

Результаты (английский) 3:

on that day, we had a lot of work, since the night we left.