Общий вопрос:
1) Do they seldom complain?
2) Will he fly his private plane to Florida?
3) Were the pirates digging for the hidden treasure?
4) Are the camels spitting at the tourists?

К подлежащему вопрос:
1) Who seldom complains?
2) Who will fly his private plane to Florida?
3) Who were digging for the hidden treasure?
4) Who are spitting at the tourists?

Альтернативный вопрос:
1) Do they complain often or seldom?
2) Will he fly his private plane to Florida or drive?
3) Were the pirates digging for the hidden treasure or searching for food?
4) Are the camels spitting at the tourists or ignoring them?

Разделительный вопрос:
1) Do they complain often, or do they seldom complain?
2) Will he fly his private plane to Florida, or will he drive?
3) Were the pirates digging for the hidden treasure, or were they searching for something else?
4) Are the camels spitting at the tourists, or are they behaving peacefully?