$A$ and $B$ are brothers,$C$ and $D$ are sisters. $A$'s son is $D$'s brother. How is $B$ related to $C$?

$A$ family consists of six members $P, Q, R, X, Y$ and $Z$. $Q$ is the son of $R$ but $R$ is not the mother of $Q$. $P$ and $R$ are a married couple. $Y$ is the brother of $R$. $X$ is the daughter of $P$. $Z$ is the brother of $P$.
Which is a pair of brothers?

$A$ boy goes to see a film and finds a man who is his relative. The man is the husband of the sister of his mother. How is the man related to the boy?

Pointing to a man on the stage,Rita said,"He is the brother of the daughter of the wife of my husband." How is the man on the stage related to Rita?

$A$ family consists of six members $P, Q, R, X, Y,$ and $Z$. $Q$ is the son of $R$ but $R$ is not the mother of $Q$. $P$ and $R$ are a married couple. $Y$ is the brother of $R$. $X$ is the daughter of $P$. $Z$ is the brother of $P$. Who is the father of $Q$?

Pointing to a person,a man said to a woman,"His mother is the only daughter of your father." How was the woman related to the person?