Perfect assumptive

The perfect 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 in turn being followed by the necessative nominative kerak.

With the verb kelmoq, 'to come':

kelgan bo'lsam kerakI have probably come
kelgan bo'lsang kerakYou have probably come
kelgan bo'lsa kerakHe/she/it has probably come
kelgan bo'lsak kerakWe have probably come
kelgan bo'lsangiz kerakYou have probably come
kelgan bo'lsalar / bo'lsa kerakThey have 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, and then the nominative kerak.

kelmagan bo'lsam kerakI have probably not come
kelmagan bo'lsang kerakYou have probably not come
kelmagan bo'lsa kerakHe/she/it has probably not come
kelmagan bo'lsak kerakWe have probably not come
kelmagan bo'lsangiz kerakYou have probably not come
kelmagan bo'lsalar / bo'lsa kerakThey have probably not come