“ Dreams may be more important than sleep. We all need to dream.” some scientists say. Dreams take up about one quarter of our sleeping time. People have several dreams each night.
     Dreams are like short films. They are usually in color. Some dreams are like old films. They come up over and over again. That may be the dreamer worrying about something. Dreaming may be a way of trying to find an answer.
     Some people get new ideas about their work from dreams. They may have been thinking about their work all day. These thoughts can carry over into dreams.
     Too much dreaming can be harmful. The more we sleep,the longer we dream. The mind is still at work when we dream. That is why we may have a long sleep and still wake up tired.

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    目前南水北调工程总体规划的12个附件和45个专题研究报告已全部完成，并通过专家审查，总体规划报告即将上交国务院。但工程沿线的水污染情况让人关注：在榆水干线规划区，骆马湖以南氨氮超标，以北至东平湖水质多为四类、五类和劣五类；黄河以北全部为劣五类。因此有关专家提出，水污染防治效果将成为决定南水北调工程成败的关键。

①0.2mol H₂O₂完全分解转移的电子数为0.4N_A

②25℃、101kPa下，16g O₃和O₂混合气体中含有的氧原子数为N_A

③将含0.1mol FeCl₃的饱和溶液滴入沸水形成的胶体粒子的数目为0.1N_A

④1molFe溶于过量稀硝酸，电子转移数为3N_A

⑤标准状况下，22.4L CHCl₃中含有的氯原子的数目为3N_A．

已知向量$\overrightarrow{AB}$与$\overrightarrow{AC}$的夹角为${120}^{\circ }$,且$\left|\overrightarrow{AB}\right|=2,\left|\overrightarrow{AC}\right|=3$,若$\overrightarrow{AP}=\lambda \overrightarrow{AB}+\overrightarrow{AC}$,且$\overrightarrow{AP}\perp \overrightarrow{BC}$,则实数$\lambda$的值为(   ）

—They are studying.