In those days, ourconcern was to provide people who were stopped by the snow storm with food and health care.
As there is less and less coal and oil, scientists are exploring new ways of making use of ______ energy, such as sunlight, wind and water for power and fuel.
In our class, when the bell rang and the teacher closed his book, it was a ______ for everyone to stand up.
Hiking by oneself can be fun and good for health. It may also be good for ______ building.
Some parents are just too protective. They want to ______ their kids from every kind of danger, real or imagined.
The loss has not yet been ______ accurately, but it is believed to be well beyond a hundred million dollars.