A、B、C、D四种金属分别用导线两两相连浸入电解液中组成原电池。A、B相连时，A为负极；C、D相连时，电流由D流到C；A、C 相连时，C极上有大量气泡；B、D相连时，D极发生氧化反应。据此判断四种金属的活动性顺序是 

A．A>C>D>B     B．D>A>B>C   C．A>D>C>B    D．C>B>A>D

情景作文。

     假设你是李华，上周五参加了学校为高三学牛举行的成人仪式。请根据

以下四幅图的顺序，向你的美国朋友Tom介绍整个活动过程，并谈谈自己

的感受。

     注意：1. 词数不少于60. 

                2. 开头和结尾已为你写好。 

     参考词汇；成人仪式  the Coming-of-Age ceremony     礼堂  auditorium

Dear Tom,

     Last Friday, I took part in the Coming-of-Age Ceremony in our school, which

was quite a meaningful occasion in my life.

     _______________________________________________________________

__________________________________________________________________

__________________________________________________________________

     That's what we did on this special occasion. Do you have similar events in the

USA? Please let me know if you do.

                                                                                                          Yours, 

                                                                                                          Li Hua