阅读短文，选择合适的答案。

    I study at Yu Hong Primary School in Guangzhou. I have forty-seven classmates (同学). Twenty-three are boys and twenty-four are girls. Our classroom is a nice one. It's very big. There are four windows and two doors in it. We have a big blackboard and a small one. The big one is for our teachers and the small one is for us. Mr. Li is our Chinese teacher. He is an old man. We don't like him at all. But Miss Chen, our English teacher, is a young woman. She is very nice. We all like her very much. So we like English the best. We often play basketball with Miss Chen.

如图所示，CDE为光滑的轨道，其中ED是水平的，CD是竖直平面内的半圆，与ED相切于D点，且半径R=0.5m，质量m=0.1kg的滑块A静止在水平轨道上，另一质量M=0.5kg的滑块B前端装有一轻质弹簧（A、B均可视为质点）以速度v₀向左运动并与滑块A发生弹性正碰，若相碰后滑块A能过半圆最高点C，取重力加速度g=10m/s²，则：

（i）B滑块至少要以多大速度向前运动；

（ii）如果滑块A恰好能过C点，滑块B与滑块A相碰后轻质弹簧的最大弹性势能为多少？

选出不同类的一项（    ）

①人生难免会经历各种各样的挫折与失败

②人们正是在战胜挫折的过程中取得成功的

③挫折是人生成长的财富，总能催人奋进

④同样是挫折，对不同的人会产生不同影响