When does the birthday party take place？（英译中)

When does the new law come into operation？（英译中)

He was admitted to the Party last year.（英译中)

He is a member of the Labor Party.（英译中)

Ms. Brown is active in the party.（英译中)

They are coming to the party as my guests.（英译中)

When does this conversation take place？A．May.B．September,C．November.D．December.