单选题:I am sorry!I took your book ______.

问题描述:

单选题:I am sorry!I took your book ______.
A.by mistake B.by mistakes

单选题:I am sorry!I took your book ______.
A.by mistake
B.by mistakes
应选:A
解析:固定短语 by mistake 错误地,by + 名词单数那 by mistakes 呢?没有 by mistakes 的说法 ^_^