Learn Dutch: De werkomstandigheden moesten snel worden verbeterd. - The working conditions had to be improved quickly.

Because the past tense is already shown by the modal verb moesten (had to). Just like in English (had to be), a modal verb in Dutch is followed by a verb in its dictionary form (infinitive). So we use the infinitive worden, not the past tense werden.

Why are both worden and verbeterd pushed all the way to the end?

In Dutch main clauses, the conjugated verb (moesten) stays in the second position, and all other verbs go to the end. Because this is a passive sentence with a modal verb, we end up with a cluster of two verbs at the end: the passive auxiliary worden and the past participle verbeterd.

Why does verbeterd end with a -d instead of a -t?

To find the ending of a past participle, we look at the stem of the verb verbeteren (to improve). If you remove the -en, you get the stem ending in -r. Because r is not in the consonant memory aid 't kofschip (or soft ketchup), the past participle gets a -d instead of a -t.

How is the long word werkomstandigheden formed?