5. Where are the children? They are watching TV in the room now. Some minutes ago they were playing a game.
В пятом предложении нужно использовать Present Continuous для выражения действия, происходящего в данный момент (now), и Past Continuous для действия, происходившего в определенный момент в прошлом (some minutes ago). Форма глагола "to watch" в Present Continuous - are watching, а форма глагола "to play" в Past Continuous - were playing.
Ответ: Where are the children? They are watching TV in the room now. Some minutes ago they were playing a game.