He stayed up late into night yesterday. This is __________ he was late for school.
When and where to build the new power station ______ yet.
_____is a good of exercise for both the young and the old.
________more attention, the work would have been done better.
Most air pollution is caused by the burning of _________ like coal, gas and oil.
I bought a dress for only 10 dollars in a sale; it was a real _________.