Revolution (Fill the gaps)

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!
It is the of the around the . It takes days, hours and 9 minutes. It causes the sucession of four different (spring, summer, autumn and ).