--Have you returned my dicionary?

--Have you returned my dicionary?
--I _____ it.Maybe you have forgotten it.
A.did returned B.did return C.did returning D.do returned
Compass and powder ______ Chinese great inwentions.They _____ centuries ago.
A.are,were invented B.is,were invented C.were,invented D.was,finished
These workers ____ the project before the end of last September.
A.was finishing B.have finished C.had finished D.finished
The girls and the boys were dancing ___ the music played by the computer.
A.to B.on C.at D.with
--I'm tired of sitting before the computer all day long.
--Why not consider ___ a rest every two hours?
A.had B.did C.having D.to have