S.+是+X+V.+的 X:a word or a phrase indicating time/place/manner. This structure emphasizes when/where/how an action or behavior took place in the past. 你是什么时候去的？ Nǐ shì shénme shíhou qù de? 我是昨天去的。 Wǒ shì zuótiān qù de. 你是在哪儿出生的？ Nǐ shì zài nǎr chūshēng de? 我是在中国出生的。 Wǒ shì zài zhōngguó chūshēng de. 你是怎么写的？ Nǐ shì zěnme xiě de? 我是用电脑写的。 Wǒ shì yòng diànnǎo xiě de.

"I am the one who come here yesterday"is this sentence translated into English. "是"means "am" in this sentance ,and "的"means "the one" in this sentence.

PATTERN II: SUBJECT + 动词短语 + 的 PATTERN III: SUBJECT + 是 ✔ 我是昨天来的 : ✔ 我昨天来的：*/✘我昨天来 ----（* means the sentence or constructure is wrong or unnatural ） Both 是 and 的 are modal particles, indicating a confirmative mood （often but not neccesarily in past tense). 我是昨天来的 strong confirmative tone 我昨天来的 slightly less strong confirmative tone Note that 的 at the end of a sentence is always not accented. In the above sentence 是 is not either, although 是 can be accented in aother use (see below). ✘ 我昨天来 When the verb is monosyllabic/single-syllabic, 的 is compulsory, or the sentence cannot stay on its own. ✔ 我昨天刚来 Here 刚and来 make up a 'phonetic word' with two syllables so that the sentence is possible. More use cases: ✔ 这件事我知道。 ✔ 这件事我知道的。（confirmative mood, in present tense） When 是 is used only by itself, it carries a consessive mood. In this case, it must be accidented and 的 will not be there at the end. 这件事我是知道，可是我没想到它会造成那么严重的后果。

"是" in your example just means (in English) = "is/am/definitely/positively", as a compact word to affirm an action. I would call it a particle- it implies your action is affirmative, so your sentence translates into "I (definitely) came in yesterday". (Some would say your example sounds strange, but I get where you are coming from.) Now "的" is also a particle, but it implies ownership of something, quite different from "是". Say, 這是我的嗎？是的。(Is this mine? Yes, it is) I've got another example here, hope it helps: 你是昨天到的嗎？ Did you arrive yesterday? 是的。Yes, I did. Sometimes, there is no literal translation for some words in English into Chinese. If you need a bit more examples, let me know~ I'll try to pull out a few more.

In Chinese, 是 (shì) is for connecting nouns, and is generally not used with adjectives. The structure for connecting nouns with 是 (shì) is: Noun 1 + 是 + Noun 2 Examples: 1.我 是 学生。 Wǒ shì xuésheng. I am a student. 2.你 是 John 吗？ Nǐ shì John ma? Are you John? Other Uses of 是 (shì) Be careful and take note. As you can see above, 是 (shì) is only used to link two nouns. It cannot be used to link a noun and an adjective. This is a very common mistake for people just beginning to learn Chinese. For that kind of sentence, you'll want to use a different structure with the linking word 很 (hěn). In Chinese it is also possible to use the phrase "是不是 (shì bu shì)?" It can be used at the beginning or end of a sentence. It's meaning is quite similar to the English word: "right" or "aren't you?" This is very useful if you want to express concern for a person, or if you want to mix up your sentence structure a bit and make it more interesting. The 是不是 (shì bu shì) pattern is also part of the affirmative-negative questions. Another way to use 是 (shì) is to use it as a tag question. You can add “是吗?” (shì ma?) to the end of a question to mean the English equivalent of: "is it" or "yeah?" Using this in a question usually allows the speaker to get a confirmation answer. Examples 1.他 没 听到，是 不 是 ？ Tā méi tīngdào, shì bu shì? He didn't hear you, right? 2.你 是 不 是 还 没 吃饭？ Nǐ shì bu shì hái méi chīfàn? Haven't you eaten yet? 3.你们 是 不 是 中 国 人？ Nǐmen shì bu shì Zhōngguó rén? Are you Chinese? 4.你 到 了，是 吗 ？ Nǐ dào le, shì ma? You have arrived, yeah? 5.你 有 两 个 孩子，是 吗 ？ Nǐ yǒu liǎng gè háizi, shì ma? You have two kids, yeah?