①实施“互联网+”行动计划

②实施精准扶贫，“小康路上一个都不能少”

③推进区域城乡义务教育一体化

④打好“蓝天保卫战”

⑤亚投行成员总数已扩至70个

已知数列{a_n}满足a_n+1= $\frac{1}{2}$ a_n²﹣ $\frac{1}{2}$ na_n+1（n∈N^*），且a₁=3．

    There is an old English saying. It tells us that we must go to bed early and get up early in the morning. Then we shall be healthy. We shall also be rich and clever. This is true. The body must have enough sleep to be healthy. Children of young age should have ten hours' sleep every night. Children who do not have enough sleep cannot do their work well and they may not be healthy.

    The body also needs exercise. Walking, running, jumping and playing games are all exercise. Exercise keeps the body strong.

    Exercise also helps the blood to move around inside the body. It is very important. Our blood moves to all parts of our body. The head also needs blood. Exercise helps us to think better.

学习了内能及能量的转化和守恒后，同学们在一起梳理知识时交流了以下想法，你认为其中正确的是（　　）