More on how people received their terumah. Specifically, the different categories of people who can eat terumah, but can't get it in the standard way - something in their status holds each of these people back... Also, a long mishnah: What if a woman doesn't wait 3 months after the death/divorce from a previous husband to remarry, and she conceives and delivers. Which raises questions whether the baby is from the first or second husband, which raises questions as to who this baby's siblings are, questions of inheritance, matters of the kehunah, and so on. The doubt is only between these two men, but the mishnah eventually takes it farther in terms of unknown paternity: "sh'tuki."