We call a verb the finite form when it shows:
– the time in which the sentence is written (either present or past): I sleep – I slept
– whether the subject of the sentence is singular or plural: you sleep – you sleep
When you’re uncertain about which of the verbs in a sentence is the infinite form, the best thing to do is to change the sentence’s time. The verb that then changes, is the infinite form.
1a. I still have to do those exercises. (Ik moet de opgaven nog maken.)
1b. I still had to do those exercises. (Ik moest de opgaven nog maken.)
2a. I look it up at Cambiumned. (Ik zoek dat op Cambiumned op.)
2b. I looked it up at Cambiumned. (Ik zocht dat op Cambiumned op.)
In non-interrogative sentences, the finite form is the second part of the sentence.