亲,首先:这里考察的是将来完成时态。将来完成时态有以下几种用法: 1. 表示动作或者状态延续到将来某一时间为止已有若干时间, 谓语动词常用延续性动词, 并常伴有for引导的时间段。
eg. By the end of next year I will have lived here for ten years.
When you come back, I will have been here for half an hour 2. 表示动作或者状态在将来某个时间之前完成, 常与by the time, when, before 等连用。谓语动词常用非延续性动词。eg.I guess you...
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