Pluperfect assumptive

The pluperfect assumptive is formed by adding to the verb stem the past participial suffix -GAN, followed by the verb bo'l- conjugated for the conditional, that is having the suffix -SA added to its stem, plus the possessive type of personal suffixes, this being followed by the necessative nominative kerak, and then by the past copula edi.

With the verb kelmoq, 'to come':

kelgan bo'lsam kerak ediI had probably come
kelgan bo'lsang kerak ediYou had probably come
kelgan bo'lsa kerak ediHe/she/it had probably come
kelgan bo'lsak kerak ediWe had probably come
kelgan bo'lsangiz kerak ediYou had probably come
kelgan bo'lsalar / bo'lsa kerak ediThey had probably come

As for the indefinite past, if the verb stem ends with -k or -g, a phonetic assimilation rule changes the suffix -GAN into -KAN (and if the verb stems ends with -g, this last consonant becomes -k).
In the same way, if the verb stem ends with -q or -g', the suffix is changed into -QAN (and if the verb stems ends with -g', this last consonant becomes -q).

The negative is formed by adding to the verb stem the suffix -MA, plus the suffix -GAN, then bo'lsa plus the personal suffix, then the nominative kerak and finally the past copula edi.

kelmagan bo'lsam kerak ediI had probably not come
kelmagan bo'lsang kerak ediYou had probably not come
kelmagan bo'lsa kerak ediHe/she/it had probably not come
kelmagan bo'lsak kerak ediWe had probably not come
kelmagan bo'lsangiz kerak ediYou had probably not come
kelmagan bo'lsalar / bo'lsa kerak ediThey had probably not come