В каких случаях в англ-яз пишется can а в каких can't?

Can (affirmative) +Can’t (negative) -Fish can swim.Horses can run.Birds can fly.We can speak Russian.Mary can sing, her voice isnice.We can read.You can go there by car.My brother can drive.A bird can’t swim.Fish can’t run.Dogs can’t fly.We can’t speak Italian.Tom’s voice is bad, he can’t sing.The baby can’t read.You can’t go there by ship.My sister can’t drive.

can-положительные предложения can't- отрицательные предложения