The 是..的 ("shi4... de") construction for emphasizing details

“是……的”结构用于强调已经发生的动作的时间、地点、方式、原因等细节。这个结构强调已知信息中的某一部分，通常用于回答具体问题或澄清事实。

The '是……的' (shì... de) construction is used to emphasize details of a past action such as time, place, manner, or reason. It highlights a specific part of known information, often used to answer specific questions or clarify facts.

使用时，把要强调的部分放在“是”之后、动词之前，句末加上“的”。如果动词有宾语，宾语通常放在“的”之后，或者也可以放在“是”之前。否定形式是在“是”前面加“不”，或者用“不是……的”。注意：这个结构多用于过去时态的动作，不用于一般现在或将来时。

To use it, place the emphasized element after '是' and before the verb, and add '的' at the end of the sentence. If the verb has an object, the object is usually placed after '的', or it can be placed before '是'. The negative form adds '不' before '是' or uses '不是……的'. Note: This construction is mostly used for past actions, not for present or future tense.