Learn Dutch: Deze klinkers zijn bijna onmogelijk uit te spreken. - These vowels are almost impossible to pronounce.

Uitspreken (to pronounce) is a separable verb. In a te + infinitive construction, the word te is always sandwiched directly between the separable prefix (uit) and the verb root (spreken), written as three separate words: uit te spreken.

Why is deze klinkers the subject of the sentence if they are the thing being pronounced?

This is a common structure where an adjective (like onmogelijk, makkelijk, or lastig) evaluates how difficult or easy an action is. Instead of using a dummy subject like 'Het' (It), Dutch often takes the logical object of the action (deze klinkers) and makes it the main subject of the sentence. The action is then tacked on at the end using the te + infinitive form.

Can I also say 'Het is bijna onmogelijk om deze klinkers uit te spreken'?

Yes, absolutely! That construction using Het is... om... te... is grammatically correct and means exactly the same thing. However, pulling the object to the front as the subject (like in the original sentence) is a very natural and common phrasing in Dutch.

If I wanted to add another adverb, like altijd (always), where would it go in this sentence?