Learn Dutch: We moeten de gevaarlijke machine ontmantelen. - We have to dismantle the dangerous machine.

The prefix ont- indicates removal, reversal, or deprivation. The root of this verb is the noun mantel, which means a cloak or coat. So ontmantelen literally means to uncloak or strip away the outer shell, which translates as to dismantle when talking about machinery, bombs, or organizations.

If I want to use ontmantelen in the perfect tense, does it get a ge- prefix?

No. Because ont- is an inseparable prefix, verbs starting with it never get the ge- prefix in their past participle form. For example, 'We have dismantled the machine' is We hebben de machine ontmanteld.

Why does the adjective gevaarlijke get an -e ending here?

This is a quick refresher on adjective endings. Because machine is a de word, and the definite article de is used right before the adjective, the base word gevaarlijk must take the -e ending.

Why is ontmantelen placed at the very end of the sentence?

This sentence uses the modal verb moeten (must or have to) as the conjugated verb in the second position. In Dutch main clauses, this structure forces the main infinitive verb, which is ontmantelen, to the very end of the sentence.