根据短文理解完成下列各题。

B

    There is an old saying: Early to bed, early to rise, makes a man healthy, wealthy and wise. It means that we should go to bed early and get up early the next morning. By doing this, we will be in good health. And we'll also be rich and clever.

    It's true that our bodies need to have enough sleep to be healthy. Children should have a ten-hour sleep every night. Those who do not have enough sleep can't do their work very well. They will not be clever and they may not get wealthy in the future.

    The body needs exercise as well. Walking, running, jumping, riding bikes and playing games are all exercise. Exercise helps to keep the body strong and fit. It also helps the blood(血液)to move around inside the body. The head needs blood too. So exercise helps people think better.

____现象的一种，它可以在____温度下进行．

M元素的一种粒子结构示意图是．

（1）若M元素组成的单质是空气的成分之一，约占空气总体积的$\frac{1}{5}$，则该单质是____．

（2）元素的化学性质与其原子的最外层电子数年有关．若x=9，M元素与下列____ （填序号）的元素化学性质相似．

（3）若x=7，M元素的这种粒子可与上图中的一种粒子相互作用形成化合物，该化合物由离子构成．写出该化合物的化学式____ 　．