The pipes have oil or water inside them, which is heated and sent to the storage tank until ______ to produce electricity.
Color-blind people often find it difficult to _____ between blue and green.
Scientists say it may be five or six years ______ it is possible to test this medicine on human patients.
If you commit a crime, you will ____ punishment.
The victims of the accident demanded that the case ______ at once.
We each took ______ tea after having ______ wonderful supper at my aunt’s yesterday.