Learner's definition of TWAIN
[noncount] old-fashioned
never the twain shall meet
—
used to say that two things, places, etc., are very different and can never be brought together or made similar二者永远合不到一起;泾渭分明 -
As far as he's concerned, work is work, family life is family life, and never the twain shall meet.对他来讲,工作是工作,家庭生活是家庭生活,二者永远也不会扯到一块儿。