一个英语句子的解释-------务必高手帮忙

一个英语句子的解释-------务必高手帮忙
（1）Several weeks ago,our headmaster,Mr.Gaudi,told usthat our school had been chosen to compete on Smart Aleck—a game show which my best friend C arla and I both love.Carla has a good imagination,and I know a lot of history,so we thought we’d be good choice for the team.
（2）A few days later,Mr.Gaudi held a meeting with everyone interested in the show.He told us that Smart Aleck uses a five member team.He also said that three more people would be needed as backup（替补）.Unluckily four times that many students were at the meeting.So Mr.Gaudi said we would have a competition and the top eight scorers would become the team and the back up.Everybody agreed that this was a fair way to decide.
（3）Yesterday,all of the hopefuls went to the dining hall after school.【We would have to decide the starting line-up（阵容）.】Mr.Gaudi acted as the host.After a couple of hours,all the places on the team were set except one.Carla and I tied for that last position.We had to hold a one-on-one competition between the two of us.The winner would be on the team and the loser would be the backup.
（4）Midway through our two-person competition,I was starting to pull ahead.Then I saw the look on Carla’s face.I waited for a second and knew what I had to do.As much as I wanted to be on Smart Aleck,Carla wanted it even more.So,starting with my next question,I held back and le t Carla win,just by a little bit.Her expression as she realized she would be on the show made up for my not being on the team.And since I will go as backup,I’ll still have the fun o f seeing the show up close.
（5）Was I cheating by not trying as hard as I could?I don’t think so.No one noticed,and Carla and I didn’t plan it.It won't hurt the team because Carla will be a very good competitor on the real show.I think that making my best friend happy was the right thing to do.
只翻译第（3）段,请标准翻译,谢谢请解释【】里的一句话,我们不得不决定开始阵容.我是不懂“汉语”意思,什么叫“决定开始阵容”,不懂.

昨天,所有预选人员都在放学后到食堂集合,【我们需要确定出赛阵容】,高迪先生做主持人.几个小时后,队伍中只剩一个角色待定了.而我需要跟卡拉进行一对一比赛,获胜者入队,另一人候补.
括号里的话并不难理解,出赛阵容 指的就是出赛的队员是哪些人.