重点讲解：
1. line up
（使）（某一批人）排成行；（使）列队；
eg. The senior leaders lined up behind him in orderly rows.
高级将领整齐有序地在他身后站成几排。
eg. The gym teachers lined us up against the cement walls.
体育老师让我们靠着水泥墙排好。
2. show up
如约赶到；出现；露面；
eg. He always shows up in a fancy car.
他总是乘坐一辆奢华轿车露面。
eg. If I don't show up for class this morning, I'll be kicked out.
如果我今天上午不去上课，我就要被开除了。
3. make a contribution to
对……做出贡献；
eg. American economists have made important contributions to the field of financial and corporate economics...
美国的经济学家们在金融和企业经济学领域做出了重要的贡献。
eg. We must make a contribution to protecting the environment.
我们必须为保护环境作出贡献。