①∀x＞0，不等式f（x）＜2x恒成立；
②∃k∈R，使方程f（x）=k有四个不相等的实数根；
③函数f（x）的图象存在无数个对称中心；
④若数列{an}为等差数列，且f（al）+f（a2）+f（a3）=3π，则a2=π．
其中的正确命题有____．（写出所有正确命题的序号）
最近你的朋友Tom在他的微博上发了这样一个帖子：
These days, I feel my school life is very boring. Every day I do the same things—taking lessons, doing exercises and taking exams. Every day I take the same way—classroom, playground and dining hall. Every day the teachers say the same thing to us: Study hard and try to enter a better high school. . .
I want to make my school life easier and more colorful. What should I do?
假如你是Jim，请你给Tom回个帖子。根据中文大意和英文提示，写出意思连贯，符合逻辑，不少于80词的短文。请不要写出你真实的校名和姓名。内容要求：
①针对Tom的困惑，先谈谈你的看法；
②结合自己的学习生活实践为他提几条合理的建议；
③ 最后送上你的祝愿。
Hi Tom,
How are you? I saw the problem in your weibo. I can understand your feelings very well.……
Love,
Jim
