In the depths of my memory, many things I did with my father still live. I call these things1and love.
    I don't remember my father ever getting into a swimming pool. But he did2the water. Any kind of3ride seemed to give him pleasure.4he loved to fish; sometimes he took me along.
    But I never really liked being on the water, the way my father did. I liked being5the water, moving through it, having it all around me. I was not a strong6, or one who learned to swim early, for I had my 7. But I loved being in the swimming pool close to my father's office and8those summer days with my father, who9come by on a break. I needed him to see what I could do. My father would stand there in his suit, the10person not in swimsuit.
    After swimming, I would go11 his office and sit on the wooden chair in front of his big desk, where he let me12anything I found in his top desk drawer. Sometimes, if I was left alone at his desk while he worked in the lab, an assistant or a student might come in and tell me perhaps I shouldn't be playing with his13. But my father always showed up and said easily, “Oh, no, it's fine.” Sometimes he handed me coins and told me to get14an ice cream…
    A poet once said, “We look at life once, in childhood; the rest is memory." And I think it is not only what we “look at once, in childhood” that determines our memories, but15, in that childhood, look at us.

①用肥皂水鉴别硬水和软水；

②冰由氧元素和氢元素组成；

③用滤纸过滤可以除去水中的所有杂质；

④电解水时生成的氢气和氧气的质量比为2：1；

⑤保持水化学性质的最小微粒是氢分子；

⑥用活性炭可以将硬水软化；

⑦净化水的方法中，蒸馏是单一净化程度最高的；

⑧水是由氢分子和氧原子组成的；

⑨活性炭可除去水中部分不溶性杂质和异味、色素等．

已知曲线y=$\frac{1}{3}{x}^3+\frac{4}{3}$，

（1）求f′（5）的值；

（2）求曲线在点P（2，4）处的切线方程．