题目

       In general, people talk about two groups of colors: warm colors and cool colors. Scientists think that there are also two groups of people: people who prefer warm colors and people who prefer cool colors.        The warm colors are red, orange and yellow. Where there are warm colors and a lot of light, people usually want to be active. People think that what red symbolizes(代表) is exciting sociable(善交际的)people who like to be with others like red. The cool colors are green, blue and purple. These colors unlike warm colors, are relaxing. Where there are coo7．“水是生命之源”这句话不仅说明水是一种重要的营养素，还告诉我们水可以溶解许多种物质，供给生命需要．小明在家做蔗糖溶于水的实验时，观察到如图现象．（1）溶解后，液面低于原水平线的微观解释是：蔗糖分子和水分子之间有一定的间隔（2）放在热水中，溶解速度加快的微观解释是：获得能量，分子运动速度加快（3）但水中溶解有不同的物质会对生命活动产生不同的影响．如鱼类可在水中呼吸，是因为水中溶有①①氧气 ②氧元素 ③氧分子（填序号）．（4）自然界的水都不是纯水，通常净化水的操作有 ①静置 ②吸附 ③过滤 ④蒸馏等；由河水生产成自来水，依次需要经过的步骤是（填序号）①②③④．