Stem لَسْ has 5 unique word forms and appears 6 times in the Quran.

Word Translation Occurrences
لَسۡتَ You are not 4
أَلَسۡتُ Am I not 2
لَسۡتُمۡ You are not 2
لَسۡتُنَّ You are not 2
وَلَسۡتُم while you (would) not 2