在正式英语中，可以省略 if，将助动词放在主语前来表达条件。

理解要点

非真实过去用 had 加主语和过去分词；假设用 were 加主语，常接 to 和动词原形；未来可能性用 should 加主语和动词原形。

例句

  • Had Maya seen the message, she would have called.如果玛雅看到了消息，她就会打电话。
  • Had we left earlier, we would have caught the ferry.如果我们早点出发，就能赶上渡轮了。
  • Were I in your position, I would ask for advice.如果我处在你的位置，我会征求意见。
  • Were the bridge to close, the village would need another route.如果桥关闭，村子就需要另一条路。
  • Should the weather change, the guide will alter the route.如果天气发生变化，向导就会调整路线。
  • Should you need help, please contact the library.如果需要帮助，请联系图书馆。

朗读使用设备上的英语合成语音，质量和可用性因设备而异；它不会评估发音。

注意事项

倒装后不要保留 if；过去条件从句中不要用 would，而要用过去分词。

自己试一试

  1. 选择正确答案。 ___ the team checked the map, they would have noticed the error. (Had / Should)

    显示答案或示范答案与解析

    Had

    Had 表明团队没有查看地图。

  2. 选择正确答案。 ___ I to move abroad, I would miss this garden. (Were / Had)

    显示答案或示范答案与解析

    Were

    Were 与 to move 一起表示假设的搬迁。

  3. 选择正确答案。 ___ any questions arise, please email the coordinator. (Should / Had)

    显示答案或示范答案与解析

    Should

    Should 引出未来可能出现的问题，主句则给出指示。

今天就用起来

选择合适的助动词，说明它表达的时间或可能性。