"The duck swims towards the goose."
Translation:Rața înoată spre gâscă.
Sometimes in Romanian you use an indefinite article where in English you would use a definite one and the other way around. It's very hard to explain exactly how and why, it's a pretty subtle thing.
only the preposition 'cu' can makes the sustantive definite. the other preposition makes the sustantive definite when it has an adjetive.