怎麼回事

what's the matter? / what's going on? / how could that be? / how did that come about? / what's it all about?

how

how? / what? / why?

exclamatory final particle

interrogative final particle

suffix, used to form interrogative 什麼|什么[shen2 me5], what?, indefinite 這麼|这么[zhe4 me5] thus, etc

tiny / insignificant

to circle / to go back / to turn around / to answer / to return / to revolve / Hui ethnic group (Chinese Muslims) / time / classifier for acts of a play / section or chapter (of a classic book)

to curve / to return / to revolve

variant of 迴|回[hui2]

(old) to report to one's master

matter / thing / item / work / affair / CL:件[jian4],樁|桩[zhuang1],回[hui2]