A、They are usually very high. B、They are always very low. C、they can be very different. D、They are actually the same. C

Science has told us so much about the moon that it is quite easy to form an idea of what it would be like to go there. It is certainly not a friendly place. As there is no air or water, there can be no life of any kind. Mile after mile there are only plains of dust with mountains around them. Above, the sun and stars shine in a black sky. If you step out of the mountain shadows, it will mean moving from terrible could in to great heat. The moon is also a very’ silent world, for sound waves can only travel through air. But from the moon, you can see a friendly sight. Our earth is shining more brightly than the stars. It looks like a huge ball, colored blue and green and brown.