qīngmíngjié hé jìniàn qīnrén yǒuguān, bú shìhé suíbiàn shuō 'qīngmíng kuàilè'

清明节和纪念亲人有关，不适合随便说“清明快乐”。

Tomb Sweeping Day is related to commemorating deceased relatives, so it is not appropriate to casually say 'Happy Qingming'