The boys were playing basketball at the sports ground at 5 o'clock yesterday.
К подлежащему: Who was playing basketball at the sports ground at 5 o'clock yesterday?
Общий: Were the boys playing basketball at the sports ground at 5 o'clock yesterday?
Специальный: Where were the boys playing basketball at 5 o'clock yesterday? или
When were the boys playing basketball at the sports ground?
Альтернативный: Were the boys or girls playing basketball at the sports ground at 5 o'clock yesterday? или
Were the boys playing basketball or football at the sports ground at 5 o'clock yesterday?
Разделительный: The boys were playing basketball at the sports ground at 5 o'clock yesterday, weren't they?