The following sentences sound natural to me but the grammatical principles appear contradictory. Are the sentences correct?
1) There WERE/ARE John and Mary in the room.
2) There WAS/IS a boy and a girl in the room.
3) There GO John and Mary.
4) There GOES the boy and his sister.
5) Where (Wh-questions) ARE John and Mary now ?
6) Where IS the boy and his sister now ?
7) HAVE John and Mary arrived ?
8) HAS the boy and his sister arrived ?
9) ARE football and tennis on TV tonight ?