在英语语法中，过去将来时的被动语态是指在过去某个时间点之后，某件事情将会被完成。这种语态通常用于描述过去的计划、预测或者承诺。下面是一些常见的例句：
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The project would have been completed by now if the team had not encountered so many obstacles.（如果团队没有遇到这么多障碍，这个项目现在已经完成了。）
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The event was supposed to have been held last week, but it was postponed due to bad weather.（这个活动原本应该上周举行，但由于天气原因被推迟了。）
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By the end of the year, the new system will have been installed in all our branches.（到年底，我们的所有分支机构都将安装上新系统。）
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The contract would have been signed already if the lawyers had not found some issues that needed to be resolved.（如果律师们没有发现一些需要解决的问题，这份合同现在已经签署了。）
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The report was supposed to have been submitted yesterday, but I forgot to send it.（这份报告原本应该昨天提交，但我忘记了发出去。）
以上这些例句展示了过去将来时的被动语态的运用情况。这种语态可以帮助我们描述过去的计划和承诺，同时也能够传达一些对未来的预测和期望。如果您想要在英语中更加流利地运用这种语态，可以多练习模仿这些例句，提高自己的语感和表达能力。
