化学就在我们身边。下表是生活中常见的两种清洁剂及其有效成分，且NaClO+2HCl=NaCl+Cl₂↑+H₂O，下列说法正确的是（　　）

已知点P（x₀，y₀）和直线y=kx+b，则点P到直线y=kx+b的距离证明可用公式d= $\frac{\left|k{x}_0-y_0+b\right|}{\sqrt{1+k^2}}$ 计算．

例如：求点P（﹣1，2）到直线y=3x+7的距离．

解：因为直线y=3x+7，其中k=3，b=7．

所以点P（﹣1，2）到直线y=3x+7的距离为：d= $\frac{\left|k{x}_0-y_0+b\right|}{\sqrt{1+k^2}}$ = $\frac{\left|3\times \left(-1\right)-2+7\right|}{\sqrt{1+3^2}}$ = $\frac{2}{\sqrt{10}}$ = $\frac{\sqrt{10}}{5}$ ．

根据以上材料，解答下列问题：

如图，在函数y₁=$\frac{k_1}{x}$（x＜0）和y₂=$\frac{k_2}{x}$（x＞0）的图象上，分别有A、B两点，若AB∥x轴，交y轴于点C，且OA⊥OB，S_△AOC=$\frac{3}{2}$，S_△BOC=$\frac{27}{2}$，则线段AB的长度是（　　）

Dear Seth,

    You are only three years.old,and at this point in your life you are not able to understand this letter.But some day when you1,I hope you will find something2in what I am going to share with you.

    Life can be3.There will be people in your life who won't be very nice.They'll4you because you are different,5for no good reason.You will also face heartbreak and might be6by those you love.I hope you don't have to face these too much,but such things7.

    Be open to life anyway.You'll find cruelty（残忍）and8n your journey through life,but don't let that9you from finding new things.I don't retreat（退却）from life,and don't10or wall yourself off.Be open to new things,new experiences,and new people.You will11many times,but if you allow that to stop you from trying,you will12 many chances.Do remember failure is a stepping stone to13

    You will meet many people who will try to do14than you,in school,in college,and at work.They'll try to have nicer cars,bigger houses,nicer clothes,and so on.To15,life is a competition.However,I believe life is a16.If you always try your best to17others,you are wasting your life.Learn to enjoy your life18and you will make it a journey of 19of learning and of love.

    Finally,know that I love you and always will.You are20a really wonderful journey,and I will always be there for you.

Love

Dad

   13－5=（  ）