最近，洛阳小伙扶摔倒老人被讹一事引起了社会的广泛关注，人们都在议论还该不该去做好事，帮助他人。而“Positive Energy”一词早已对我们中国人产生了很大影响，因此，很多人并不会因此就不去做好事了。瞧！你身边就有很多助人为乐的同学，他们的事例值得我们学习。请根据下面表格信息给学校校刊写一篇短文，谈谈身边的好人好事，号召大家向他们学习。词数60—80（开头和结尾已给出，不计入总词数）

Dear Editor,
    In our school, some students are always thinking more of others and ready to help them. I am moved deeply. Here is what they usually do.
    Liu Chang is a very good student.
    I hope everyone can learn from them and do something for others.
                                                                                                                                                             Yours, 
                                                                                                                                                           Mark 

发电机的发明，开辟了人类电气化的时代，而电动机应用，出现在社会生活的各个方面．如图甲和乙，能说明是电动机工作原理的是____，能说明是发电机工作原理的是____．（以上两空填“甲”或“乙”）

如图，AB＝AC，CD⊥AB于D，BE⊥AC于E，则图中全等的三角形对数为（　）