China ’s Marriage Law stipulates that it is forbidden to marry an immediate blood relative with a blood relative within three generations. A direct blood relative refers to a relative who has a direct blood relationship with himself. All blood relatives except blood relatives. According to the above definition, A and B of the following options can be married:. ['Zhang is the uncle of A (female), and the son of Zhang.', 'Li is the uncle of B (female), the son of Li.', 'A is the son of Lin and his ex-husband, B is the daughter of Lin and his future husband.', "Wang is Zhang's uncle, A is the son of Wang, and B is the daughter of Zhang."]