[4.2.1退款的原则](4.2.1%E9%80%80%E6%AC%BE%E7%9A%84%E5%8E%9F%E5%88%99.md) [4.2.2退款的手续](4.2.2%E9%80%80%E6%AC%BE%E7%9A%84%E6%89%8B%E7%BB%AD.md) [4.2.3退款的效力](4.2.3%E9%80%80%E6%AC%BE%E7%9A%84%E6%95%88%E5%8A%9B.md) [4.2.4特殊情形的处理](4.2.4%E7%89%B9%E6%AE%8A%E6%83%85%E5%BD%A2%E7%9A%84%E5%A4%84%E7%90%86.md)