Discovery in a South African cave suggests that modern human behavior ____ much earlierthan ____.
7. No one but her parents _____ it.
6. The Olympic Games _____ held every _____ years.
5. About 40 _____ of the population of that country _____ on farms.
4. _____ can be done _____ been done.
3. He played on the _____ for two hours and when he returned he found half his goods _____ stolen.