be no/without rhyme or reason idiom
毫无道理;莫名其妙
to be without any obvious reasonable explanation
Government money was given out to some people and not to others, apparently without rhyme or reason. 政府的钱发给一些人，而不给另外一些人，这样做显然毫无道理可言。
There is no rhyme or reason to her behaviour. 她的行为反复无常。