irresponsible
adj
(of people, actions, etc) not showing a proper sense of responsibility (指人、 行为等)不负责任的, 没有责任感的
an irresponsible child 没有责任感的孩子* irresponsible behaviour 不负责任的行为
It is irresponsible of you not to prepare students for their exams. 你不帮助学生准备考 试就是不负责. Cf 参看 responsible 4.
Then, her composure regained, she was ready to set off with the porter's assistance to search for nay intruders who might still be lurking in her flat.