be neither one thing nor the other idiom
是非此非彼的混合物;既不是此，也不是彼
to be a mixture of two different things, often things that do not combine well
I prefer a book to be either fact or fiction - this one is neither one thing nor the other! 我喜欢的书要么写实，要么虚构——这本书却是个四不像！