Strangers always leave before she gets to the hotel, and strangers leave before she gets to the hotel.
She can't sit still until her motherland is free. She couldn't sit still until her motherland was free.
Tony was depressed because he couldn't go swimming.
We have never thought about anything wrong, and we have never thought about anything wrong.
She refrained from laughing. She held back and didn't laugh.
This is how these English sentences are translated, but I don't understand your positive and negative translation.