唐代诗人白居易与友人游江西庐山，宿大林寺。当时为农历四月初九，山上梨桃始花，作诗“人间四月芳菲尽，山寺桃花始盛开”请你判断形成这种现象的主要原因是（    ）

已知：

①浸出液含有的阳离子主要有H⁺、CO²⁺、Fe²⁺、Mn²⁺、Al³⁺等；

②部分阳离子以氢氧化物形式沉淀时溶液的pH见表（金属离子浓度为0.01mol/L）：

③CoCl₂•6H₂O熔点为86℃，加热至110～120℃时，失去结晶水生成无水氯化钴．

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