by mistake 错误地
例句：I took his schoolbag as mine by mistake.我误将他的书包当作我的拿走了.
mistake A for B 误将A当作B
例句：The students mistook me for their teacher.学生们把我误认为他们的老师了.
make a mistake 犯了个错误
例句：She made a mistake by taking the wrong textbook to class.她犯了个错,上课拿错了课本.