只知其一,不知其二 [ㄓˇ ㄓ ㄑㄧˊ ㄧ , ㄅㄨˋ ㄓ ㄑㄧˊ ㄦˋ; zhi3 zhi1 qi2 yi1 , bu4 zhi1 qi2 er4] to know the first, but not know the second (idiom); only partial information ◄ ►