float      manure      permanent      pollution      roots      Sound      sun      tasteless      Wool   
Choose the correct word from the list above to fill in each blank.
Plants take water from the soil by the .
A hydro-electric power station does not cause .
Animals such as cows provide us with which is good for farming.
Oil and petrol on water.
Pure water is colourless, odourless and .
is obtained from sheep.
energy of the voice is transformed into electrical energy in a telephone.
A natural source of heat energy and light energy is the .
Milk teeth are replaced by teeth.