Here is the item:
At the video arcade, Jeremy wished that he had slew the giant mutant tomatoes on level one. Then he would not have fought the kamikaze pickles on level two and could have kept his grape bombs for the ninja carrots on level three.

The first verb, had slew, is the problem. As you know, this verb requires the past participle. Had slain is the correct verb.

Verb Simple
Present
Simple
Past
Past
Participle
slay slay(s) slew or slayed slain

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