根据中英文提示,完成句子。

1．像许多足球运动员那样,当他很小的时候就开始了训练.

Like many football players, he ________________________________.

2．他们计划开办自己的公司.

They ____________________________ their own company.

3．刘翔是中国最受欢迎的运动员之一.

Liu Xiang ________________________ sportsmen in China.

4．除非我的朋友也被邀请,否则我也不去旅游.

I won't take a trip to anywhere unless my friend ________________________, too.

5．妈妈告诉我比赛后要尽快回家.

My mother told me ________________________ the match was over．

三段式加热制度的特点是什么？