Locate the throat consonant in the examples:
PerfectMeaningThroat consonant position
مَنَعَPreventedThird radical: ع
سَلَخَSkinnedThird radical: خ
جَحَدَDeniedSecond radical: ح
نَهَضَRose upSecond radical: ه
ذَهَبَWentSecond radical: ه
The relevant consonant may be the second or third radical. First identify the root's ف–ع–ل positions before applying the phonetic observation.