free on board plane

例句：

1. 1.The airline offers free in-flight entertainment to passengers.
   航空公司为乘客提供免费的机上娱乐。
2. 2. The economy class ticket is free on board the flight.
   经济舱的机票在飞行过程中是免费的。
3. 3. The first-class passengers are entitled to free meals and drinks on board the plane.
   头等舱乘客有权在飞机上免费享用餐食和饮料。