1. Welcome board!
欢迎登机！
还能这样说：
Welcome to go board!
Welcome to take the flight!
应用解析：
above board 诚实地；光明正大地；
a groaning board 丰盛宴席；
across the board 全面的；
go on board 上船；上飞机；
go on the boards 当演员
2. Please keep your seat belt fastened.
请系好安全带。
还能这样说：
Put on your seat belt, please.
Fasten your seat belt, please.
应用解析：
fasten one's eyes on sb. 盯住某人；
fasten the dyes into the cloth 使布深染而不褪色；
fasten upon a pretext 抓住某种借口；
fasten a crime on sb. 加罪于某人
3. Your seat is in the middle of the cabin.
您的座位在客舱中部。
还能这样说：
You can sit in the center of the passenger compartment.
You can take a seat in the middle of the passenger compartment.
应用解析：
cabin作名词：小屋，a log cabin 圆木小屋，舱房；船舱；
cabin还可以作动词：蛰居于小屋；把……关进（狭小的地方）。
4. Do you have any medicine for airsickness?
你们有没有晕机药？
还能这样说：
Do you have pills for airsickness?
Could you give me some airsickness medicine?
应用解析：
give sb. a taste of one's own medicine 以其人之道，还治其人之身