为了测量冰块的密度，把水注满可均匀膨胀，质量和厚度忽略不计的正方体模具中，塞紧注水孔，利用天平测得水的质量．

阅读下面短文。从短文后所给的A、B、C三个选项中选出最佳选项。

    Light travels at a very fast speed. It is about a million times 1 than the speed of sound. You can get some idea of this 2 by watching the start of a race (赛跑). If you stand some distance away from the starter, you can see smoke from his gun before the sound gets to your 3

    This great speed of light4some strange facts. Sunlight 5about 8 minutes to get to us. If you look at the light of the moon tonight, 6 that the light rays (光线) left the moon 1.3 seconds before they got to you. The nearest star is so 7 away that the light which you can see from it tonight started to 8 towards you several years ago. In some cases, the light from one of tonight's stars had started on its journey to you before you were born.

    So, to be exact, we can't say, "The stars are shinning 9." We have to say instead, "The stars 10 pretty. They were shining several years ago, but their light has only just got to the Earth."