His mother would alternate inexplicably between kindness and cruelty.他母亲会莫名其妙地时而和蔼时而凶暴。She suddenly and inexplicably announced her retirement.她突然不知缘由地宣布退休。His wartime experiences were inexplicably absent from the diaries.他的战时经历莫名其妙地从日记中缺失了。The files have inexplicably disappeared.那些文件莫名其妙地消失了。