You will recall a regular verb takes a GE- prefix in the past tense. They do not have another prefix already on the root, and there are not two roots forming one word, like under+stand = understand. So, it would be a verb like STAND.
A prefixed is just like a regular verb, BUT it already has a prefix as part of the verb.
For example, KOOP is a regular verb, and VERKOOP is a prefixed verb. The rule with prefixed verbs are that they do NOT take the GE_ prefix in the past tense.
REGULAR VERB: STAAN — Ek staan in die water. (present)
PREFIXED VERB: VERSTAAN — Ek verstaan die woorde. (present)
REGULAR VERB: STAAN — Ek het in die water gestaan. (past)
PREFIXED VERB: VERSTAAN — Ek het die woorde verstaan. (past)
PREFIXED VERB: VERSTAAN — Ek sal die woorde verstaan. (future)
PREFIXED VERB: VERSTAAN — Ek WIL die die woorde verstaan. (modal)
Also make it future or past tense.
Make any of these sentences above a question or state as a negation.