First -paraphrasing with unless
I won't invite her if she doesn't apologise to me.
Unless she apologises to me, I won't invite her.
She knows a lot about science because she watched a lot of documentaries.
If she didn't watch a lot of documentaries, she wouldn't know a lot about science.
We got lost last night because we forgot the GPS.
If we hadn't forgotten the GPS we wouldn't have got lost.
You will understand the text if you read it thoroughly.
You won't understand the text unless you read it thoroughly.
There are too many cars. As a result, our planet is polluted.
If there weren't so many cars, our planet wouldn't be polluted.
You ate the whole cake. That's why you threw up.
If you hadn't eaten the whole cake, you wouldn't have thrown up.
Unless it's cold, we'll have the party outdoors.
They do not have tickets for the concert, so they stay at home.
If they had tickets for the concert, they wouldn't stay at home.
If Sarah hadn't overslept, she would have attended the class.
Unless you kick the ball very hard, it won't reach its goal.
If you don't kick the ball very hard, it won't reach its goal.
I can't find my glasses. I can't read the newspaper.
If I found my glasses, I could read the newspaper.
We only came by bus because there were no taxis.
If there had been taxis, we wouldn't have come by bus.
You shouldn't eat fish unless it's fresh.
You shouldn't eat fish if it's not fresh.
I suggest asking the police for directions.
If I were you, I would ask the police for directions.
I didn't go to see Helen because I didn't know she was in the hospital.
If I had known she was in the hospital, I would've gone to see her.