Let goed op!
Ik wil opletten.
Ik heb opgelet.
Pay close attention!
Yes. opletten splits into op + letten. In a main clause the prefix goes to the end: Let goed op!
The perfect tense is "Ik heb opgelet" — the -ge- slots between the prefix and the stem.
opletten means "to pay attention". Example: Let goed op! (Pay close attention!)
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