1) They seldom stay at home during their summer holidays, don't they?
Do they seldom stay at home during their summer or winter holidays?
When do they stay at home?
Who stays at home during the summer holidays?
Do they seldom stay at home during their summer holidays?
2) Did he water plants in the garden yesterday?
Did he or she water plants in the garden yesterday?
Where did he water plants yesterday?
Who watered plants in the garden yesterday?
He watered plants in the garden yesterday, didn't he?