what makes you think ... ? – Russian translation

с чего вы взяли, что ... ? (‘Are you still looking for that mouse?' ‘That's right. I thought I saw it run under there, and I was about to deal with it regardless of its age or sex.' ‘What makes you think there is a mouse here?' ‘Oh, one gets these ideas.' ‘Do you often hunt for mice?' ‘Fairly frequently.' (P.G. Wodehouse) ART Vancouver)