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pl是… 的 is a common and multifunctional structure in Chinese. This guide focuses only on the most common functions relevant for beginners.
While the 是… 的 structure appears simple on the surface, it poses several challenges for learners. Its syntactic pattern differs from English, its meaning is context-dependent, and its usage requires sensitivity to discourse and pragmatic intent.
Common errors
1. Incorrect position
1.1 是 is placed before the aspect of the sentence that is emphasised.
This might confuse learners and make them uncertain where to place 是.
*他们昨天是到的。
*是他们昨天到的。
他们是昨天到的。
*他們昨天是到的。
*是他們昨天到的。
他們是昨天到的。
1.2 是 is placed directly in front of the verb.
*我坐地铁是来的。
我是坐地铁来的。
*我坐地鐵是來的。
我是坐地鐵來的。
1.3 Learners might mistakenly place a pronoun object after 的.
*我是在学校认识的她。
我是在学校认识她的。
*我是在學校認識的她。
我是在學校認識她的。
2. Confusion as to when 是 can be left out of the structure
Learners might be uncertain when 是 can be left out of the structure. It can be left out of the structure in affirmative sentences, especially in spoken language or when the emphasis is clear from context. In a negative sentence 是 cannot be left out.
*他们不昨天到的。
他们不是昨天到的。
*他們不昨天到的。
他們不是昨天到的。
3. Confusing the 是… 的 structure with the aspectual particle 了
Both the 是… 的 structure and the aspectual particle 了 are used about past actions. This might confuse learners, making them unsure when to use which or use both in the same sentence. The aspectual particle 了 indicates the completion of an action, while the 是… 的 structure presupposes the completion and instead draws attention to circumstances surrounding the action. Consequently, the two are mutually exclusive and do not co-occur in the same sentence.
*我是到的。
我到了。
*我是到的。
我到了。
*我是在家吃了晚饭的。
*我在家吃了晚饭。
我是在家吃晚饭的。
*我是在家吃了晚飯的。
*我在家吃了晚飯。
我是在家吃晚飯的。
4. Using the 是… 的 about actions that have not yet occurred or are not completed
Learners might use 是… 的 about actions that have not yet occurred or are not completed. The structure should not be used for future intentions unless referring to scheduled facts.
*我是明天去北京的。
我明天去北京。
*我是明天去北京的。
我明天去北京。
他是明天出发的，对吧？
他是明天出發的，對吧？
5. Overusing the 是… 的 structure
Overusing 是… 的 when there is no communicative need to highlight a detail.
*我是星期五吃饭的。
*我是星期五吃飯的。
Here the sentence without 是… 的 would be appropriate.
我星期五吃饭。
我星期五吃飯。
6. Using 是…的 when introducing a new event
是…的 indicates the action is already known or established in discourse. Using it to introduce new information can confuse the listener.
*他是去商店的。
他去商店了。
*他是去商店的。
他去商店了。
L1 inference error
The lack of a direct English equivalent for 是…的 might make it more difficult for learners to understand both how and when the structure is used. Although it can be useful to compare it to the English ‘it was… that…’, this might lead to learners forcing emphasis in every past sentence.