非限制性关系从句中的重复信息大部分可以省略，如：
Robert, who is our teacher, likes fishing. 罗伯特是我们的老师，他喜欢钓鱼。
MC: Robert likes fishing.
NRC: who is our teacher.
→ Robert, our teacher, likes fishing.
*NRC采用了DOING的简化形式。
The building, which was painted red, looks very attractive. 这座建筑被粉刷成了红色，看起来非常漂亮。
MC: The building looks very attractive.
NRC: which was painted red.
→ The building, painted red, looks very attractive.
*NRC采用了DOING的简化形式。
His first book, which will be published next month, is based on a true story. 他的第一本书将于下个月出版，其来源于一个真实的故事。
MC: His first book is based on a true story.
NRC: which will be published next month.
→ His first book, to be published next month, is based on a true story.
*NRC的谓语动词块的时间为将来，采用了TO DO的简化形式。
The old man, who has worked abroad for twenty years, is on the way back to his motherland. 这位老人已在海外工作了二十年，现在正在回祖国的路上。
MC: The old man is on the way back to his motherland.
NRC: who has worked abroad for twenty years.
→ The old man, having worked abroad for twenty years, is on the way back to his motherland.
*NRC采用了DOING的简化形式。
It rained heavily in the south, which caused serious flooding in several provinces. 南部大雨滂沱，使好几个省发生了严重的水灾。
MC: It rained heavily in the south.
NRC: which caused serious flooding in several provinces.
→ It rained heavily in the south, causing serious flooding in several provinces.
*which指it rained heavily in the south。NRC采用了DOING的简化形式。
He missed the train, which was a great pity. 好可惜，他错过了火车。
MC: He missed the train.
NRC: which was a great pity.
→ He missed the train, a great pity. *which指He missed the train。
Mike found his missing car in the street outside his house, which looked newly cleaned and polished. 麦克发现他丢失的汽车在自己房子外面的街道上，看起来刚被清洗并抛光过。
MC: Mike found his missing car in the street outside his house.
NRC: which looked newly cleaned and polished.
→ Mike found his missing car in the street outside his house, looking newly cleaned and polished. *which指his missing car。
通过分析大量来自权威语料库的句子，作者总结出了非限制性关系从句的简化规则，如下表所示：
| 简化规则 | 示例 | |
|---|---|---|
| 1. 当NRC的谓语动词块不含情态动词时 | 1.1 当关系代词是NRC的主语时 | — |
| 1.1.1 当NRC的谓语动词块的时间是将来或过去将来 | 通常采用TO DO的简化形式：His first book, which will be published next month, is based on a true story → His first book, to be published next month, is based on a true story. | |
| 1.1.2 当NRC的谓语动词块的时间是现在 | — | |
| 1.1.2.1 当NRC的谓语动词块的状态为完成或完成进行 | 通常采用DOING的简化形式：The old man, who has worked abroad for twenty years, is on the way back to his motherland → The old man, having worked abroad for twenty years, is on the way back to his motherland. | |
| 1.1.2.2 当NRC的谓语动词块的状态为进行 | 通常采用DOING的简化形式：The famous singer is traveling across the country, promoting her new album. | |
| 1.1.2.3 当NRC的谓语动词块的状态为一般 | 通常采用DOING的简化形式：The experiment, intended to test the theory, will be carried out tomorrow. | |
| 1.1.3 当NRC的谓语动词块的时间是过去 | — | |
| 1.1.3.1 当NRC的谓语动词块的状态为完成或完成进行 | 通常采用DOING的简化形式：The twins, who had been separated for so long, held each other and burst into tears → The twins, having been separated so long, held each other and burst into tears. | |
| 1.1.3.2 当NRC的谓语动词块的状态为进行 | 通常采用DOING的简化形式：The park was full of people, enjoying themselves in the sunshine. | |
| 1.1.3.3 当NRC的谓语动词块的状态为一般 | — | |
| 1.1.3.3.1 当NRC的谓语动词块的第一部分是BE | 通常采用DOING的简化形式：The building, which was painted red, looks very attractive → The building, painted red, looks very attractive. | |
| 1.1.3.3.2 当NRC的谓语动词块的第一部分是静态动词 | 通常采用DOING的简化形式：Romeo, believing that Juliet was dead, decided to kill himself. | |
| 1.2 当关系代词不是NRC的主语时 | 通常NRC不能简化，关系代词也不能省略。 | |
| 2. 当NRC的谓语动词块含有任意以下情态动词（且含有如括号里所示的意义）时： can/could (表可能性)；should/ought to (表建议) | 通常采用TO DO的简化形式：This herb, which can be found in Asian, is poisonous → This herb, to be found in Asian, is poisonous. | |
A. 尝试简化以下句子中的关系从句。
B. 单选：选择最合适的答案。
注：此处仅保留部分代表性练习，完整练习请参考纸质版或后续版本。