乘客 (chéngkè) is a noun meaning "passenger," referring to someone traveling in a vehicle such as a bus, train, or airplane. It is composed of 乘 (to ride) and 客 (guest). For example, 告诉了乘客 means "informed the passengers."
所有乘客请系好安全带。
suǒyǒu chéngkè qǐng jìhǎo ānquándài.
All passengers, please fasten your seatbelts.
地铁里的乘客太多了,挤不上去。
dìtiě lǐ de chéngkè tài duō le, jǐ bú shàngqù.
There are too many passengers on the subway; I can't squeeze on.
航空公司为乘客提供了免费的饮料。
hángkōng gōngsī wèi chéngkè tígōngle miǎnfèi de yǐnliào.
The airline provided free drinks for the passengers.