1、I: The Subject
"I" is a nominative pronoun, which means that it is used as the subject of a sentence, or as a predicate nominative.
I是主格代词，意思是用作句子的主语，或谓语主格
A predicate nominative (also called a predicate noun) is a word or group of words that completes a linking verb and renames the subject.
谓语主格(也称为谓语名词)是一个词或一组词，它补全了系动词后的成分并重新命名主语。
比如说：
I went to the store.
我去商店。
In this case, "I" is the subject of the sentence - the person who performed the action of going to the store. This sentence is correct because it uses "I" as the subject.
You also use "I" as a predicate nominative after a "to be" verb.
在这个例子里，I是这个句子的主语-去商店这个动作的承担者。像这样在作为句子的主语出现时用I是正确的。你也可以当我为谓语主格时用I。
例句：
It is I who went to the store.
是我去了商店。
In this case, "I" comes after the verb "is" and is a the predicate nominative, or another name for the subject of the sentence - in this case, "it." This may sound unusual, because many people colloquially say, "It's me," but using "I" in this way is grammatically correct and preferable in formal English.
在这种情况下，I跟在动词is后面，是谓语主格，与句子主语——在这个句子里也就是it，等同一意。这听起来可能不太寻常，因为很多人口语化地说“It’s me”，但在正式英语中以这种方式使用“I”在语法上是正确的，而且更可取。
2、Me: The Object
"Me" is an object pronoun, which means that it serves as a direct or indirect object to the verb or as the object of a preposition.
Me是宾语代词，意思是作为动词的直接或间接宾语或介词宾语。
例句：
Mom hugged me.
妈妈抱了我。
In this sentence, "me" is the direct object of the verb "hugged" because it receives the action of hugging. This sentence is correct because it uses "me" as the direct object.
在这个句子里，“我”是“抱”这个谓语动词的直接对象，因为我接受了“抱”这个动作。这样的句子中用“me”宾格是正确的。
例句：
Mom bought me a snack.
妈妈给我买了零食。
Likewise, this sentence uses "me" as an indirect object.
类似的，这个句子中“我”作为间接宾语用“me”。
Mom bought a snack for me.
妈妈给我买了零食。
In this sentence, "me" is the object of the preposition "for" and is also correctly used. Note that this sentence conveys the same meaning as the previous one, but it's constructed a bit differently.
在这个句子中，me是介词for的宾语，这样也是正确的。请注意，这个句子表达的意思与前一个相同，但结构略有不同。
3、典型错误
①Jack and me got home late.
In this sentence, there are two subjects "Jack and me," but me is the objective case. As it's a subject, the correct pronoun is "I."
在这个句子中，有两个主语“Jack和我”，但是me是宾格形式。但是其实“我”是主语，所以正确的代词应该是I。
A good way to check is to remove the other people at the beginning of the sentence and re-read the sentence to see if it sounds right ("Me got home late" does not!).
有一个检查它的好方法就是你可以移除掉句子开头的其他人，并重新读一遍这个句子听一下是否顺耳。（比方这个句子就变成了，“Me got home late”，很明显并不顺耳。）
②The snobby girl thinks she's above my family and I, but she's not.
This is another example of how multiple objects adds confusion. Here "I" is incorrectly used as the object of the preposition "above," but it should be "me."
这是有多个对象导致句子变混乱的一个例子。这里“我”被错误地用作了主格形式，而其实它是above的宾语，应该是me。
③It wasn't me.
This one trips up a lot of people as it can't be checked by ear, like the examples above. Though this is a common colloquial phrase, it is not grammatically correct. In this sentence, "was" is a form of the verb to be that sets up a predicate nominative, so the writer should use "I," which is in the nominative case.
这一个会绊倒很多人的句子，因为这听起来并没有任何不适，就像上面的例子一样。虽然这是一个常见的口语化短语，但它在语法上是不正确的。在这个句子里，was是系动词，由此之后出现了一个谓语主格，所以这句话应该用主格形式“I”。
但事情也不是绝对的，现在的年轻人更愿意把“It's me.”挂在嘴边，虽然在语法上是错误的，更多成为了一种非正式说法。“It's I.”则更正式一些，在现代人听来可能有点过时。
4、正确用法例句
同学们可以多读正确例句来培养自己的语感
I went to the mall yesterday.
She and I don't always get along, but we try.
The cat scratched me when I tried to pet her.
Are all those presents really for me?
Will you please give me the rest of your ice cream cone?
It is not I you should blame.
I called Jason for help with my homework.
Give the recipe to Jim and me, and we'll cook you a delicious breakfast.
When will I get my sunglasses back?
The boys and I want to take a vacation this summer.
最后：
语录网网友观点：既然知道it's me实际上不仅没问题，而且更常用，你还在标题里暗示它是错的？,英语和中文一样有古今异义 用法应该不断改进,It is I who went to the store.
是我去了商店。
不就是个强调句型吗？,