to stop (doing something)
The preposition is part of the word. Without it the answer is wrong in ripiti: ophouden met, not ophouden.
On the card “to stop (doing something)”, ripiti also accepts stoppen met. Not the other way round: for stoppen met, ophouden met is not accepted.
Remember ophouden met for good. ripiti brings the word back just before you forget it, with these sentences. Free, no account needed, works offline.
practise ophouden met in ripiti