Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

1. Pollution is harmful to plants, a and people.
2. Three sources of energy that don't pollute the Earth are the sun, water and w.
3. Hydroenergy is the energy of w.
4. Windmills turn wind energy into e.
5. S energy comes from the word sol.