我们的备用发电机是电力系统的最后保障。

Our backup generator serves as the final ___backstop for the power system.

击球手用力过猛，球直接飞过了本垒板撞在了挡网上。

The batter swung too hard, and the ball flew over home plate and hit the ___backstop.

银行同意为这笔交易提供担保，以防止出现任何违约风险。

The bank agreed to ___backstop the deal to prevent any default risks.