1. Expression：keep a straight face

Explanation: To have an emotionless facial expression. （板着脸）

Example：It's so hard to keep a straight face on camera when you have hilarious co-stars like I do.

当你有像我这样滑稽的合作明星时，很难在镜头前板着脸。

“I don't see that there's anything funny about it,” he said, offended. “Of course there isn't,” she said, trying to keep a straight face.

他生气地说：“我看不出有什么可笑的。”她尽量板着脸说：“当然没有。”

When Bob fell into the water, he looked funny and I could hardly keep a straight face.

鲍布掉入水中时，看起来很滑稽，我几乎禁不住笑出来。

Chu Yin-chiu did his best to keep a straight face as he walked slowly into the drawing-room, and stood looking out at the delegates, a frown on his face.

朱吟秋忍住了笑，慢慢地踱到客堂里朝外站着，皱了眉头。（子夜）

2. Expression：inside track

Explanation：An advantage over someone or something. （优势，领先）

Example：I hope I have the inside track on the competition, thanks to my extensive student teaching experience.

由于我丰富的学生教学经验，我希望我能在竞赛中占得先机。

He has the inside track in the election because his father was so well known and admired.

他在竞选中处于有利地位，因为他父亲非常出名而又受人钦佩。

All the candidates look OK, but Hester has the inside track because she’s single.

看上去所有候选人都不错，不过赫斯特占有明铋显优势，因为她是单身。

John was on the inside track for the position because he had the best marks.

约翰最有可能获得这个职位，因为他分数最高。