图中四位同学正在讨论某一化学方程式表示的意义，他们所描述的化学方程式是（　　）

A

Dear Uncle，

    I have finally arrived !It was such a difficult journey, but now I'm here，ready to begin my new life．I'm staying in a hostel(青年招待所)and I'm sharing a room with ten other men．This evening，I' m meeting a friend from our country, and he's going to help me to find a job．

    I hope you are all well．

Yours,

Barry

Dear Uncle，

    It's so cold here．Tonight they say it's going to snow．That will be a new experience for me, but I don't think I'll enjoy it because I'll be outside in the cold．You found work carrying boxes in a big market during the night．It's tiring，so I hope I will find something better soon．

    You can write to me at the address on the back of this letter．It's a restaurant I go to often．Give my love to everybody and write soon．

    Yours，

    Barry

Dear Uncle，

    Thank you for your letter．I'm glad that my cousin is doing well at school．

    Things are getting better here．I've found a flat(公寓)and I'm moving in tomorrow with two friends．It's very small, but it's better than the hostel．And I won't have to work in the market anymore，because I'm going to work at the restaurant I told you about in my last letter．From now on，I'll have a warm place to work，and I'll get free meals．

    Yours．

    Barry

2009年11月17日历经两个多小时的手术后，家属发现病人骨折的右腿依旧肿胀，没有任何手术迹象；而原本好好的左腿，却“无辜被手术”，植入一块钢板，并打上厚厚的石膏绷带。这起离奇的手术就发生在湖北通城县中医院骨科手术室，患者是84岁高龄的老人赵荣彬。