A series of experimental facts for LnBa_2_Cu_3_O_7-y_ single crystals indicate that imperfect structure and non-uniformity composition in samples have an important effect on their normal state resistivity, normal-superconductive transition behavior, T。and critical current and so forth. We think that in imperfect single crystals, there also exist superconductive glass state effects, similar to single phase polycrystal LnBa_2_Cu_3_O_7-y_ samples.