1. They haven't bought a new house yet.
    Have they already bought a new house?
2. The children haven't built a house yet.
    Have the children already built a house?
3. The painter hasn't finished the picture yet.
    Has the painter already finished the picture?
4. The baby hasn't fallen asleep yet.
    Has the baby already fallen asleep?
5. Winter hasn't begun yet.
    Has the winter already begun?