下列是对四种动物类群的代表动物形态结构特征的描述，正确的是（    ）

如图所示为一水平直路面，AB的长度为x₁=25m，BC的长度为x₂=97m，一辆汽车（视为质点）从A点由静止启动，开始做加速度大小为a₁=2m/s²的匀加速直线运动，进入BC段时先做加速度大小为a₂=1m/s²的加速运动，运动到离C点适当距离处开始以大小为a₃=2m/s²的加速度减速运动，汽车恰好能停在C点，求：

学生会要表彰一批优秀学生，Tom想推荐他的同学John竞争最乐于助人奖(Most Helpful Student Award)。请以Tom的名义给学生会主席写一封推荐信。词数约80，不包括已给出的开头和结尾。
推荐信中必须包括下列要点：John
1、有礼貌，勤奋，乐于助人，常帮助同学学习
2、聪明，记忆力好，学东西很快
3、经常为希望工程募集物品，照顾老年之家的老人
4、电脑用得好，经常为帮扶俱乐部(the Helping Hands Club)从网上获取资料
5、上周，一个小男孩迷路，John将他送回家，男孩的父母很感激他。
Dear Sir
I would like                                                              
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
We will be glad if he can win the award.
Thank you
Yours faithfully
Tom
Best wishes for you!  Hope to see you soon!