advance payment for services

例句：

1. 1. We need to make an advance payment of $500 for the new software.
   我们需要提前支付500美元购买新软件。
2. 2.The company requires a 20% advance payment before starting work on the project.
   该公司要求在开始项目工作前支付20%的预付款。
3. 3. The client agreed to pay the full amount in advance, but they never followed through.
   客户同意提前支付全部金额，但他们从未履行承诺。