Complex sentence: In a high- "T" c superconductor, the mechanism is extremely similar to a conventional superconductor, except, in this case, phonons virtually play no role and their role is replaced by spin-density waves.
Split into simpler sentences: In a high- "T" c superconductor, the mechanism is extremely similar to a conventional superconductor. Except, in this case, phonons virtually play no role and their role is replaced by spin-density waves.