What is the sky? Where is it? How high is it? They aren't easy to ___(1)___, are they? Is the sky blue? The sky has no colour. Is the sky full ___(2)___ air? We know that there is air around the ___(3)___. When planes fly, they need ___(4)___. Planes can't fly very ___(5)___ because when they go higher, the air gets ___(6)___. If we go far away from the earth, we ___(7)___ there is no air. Maybe we can answer some of our questions now. What's the sky? ___(8)___ , ___(9)___ is it? It's all around the world. The sky is a space. In this space, there is nothing ___(10)___ the sun, the moon and all the stars.