は vs が

は
1）說明
2）否定
3）は疑
4）は問は答
5）〜は〜が〜は 對比句

が
1）限定
2）疑が
3）が問が答
4）現象文
5）條件句子

AはBが
1）能力（できます、わかります）
2）所屬（あります、います）
3）情感（好き、嫌い）
4）部份所屬

P.S.
は emphasizes on the sentence after it while が emphasizes on the sentence before it.
The whole sentence is applicable to the topic/subject denoted by は while only the sub clause is applicable to the subject denoted by が.
が is used for new information while は is used for something already known.

以上視頻來自王可樂的日語教室

	は	が
Denotes	Topic (and subject)	Subject	が denotes a subject 主語 but not topic 主題 は denotes topic 主題 which can also be the subject 主語
Importance	Sentence after は	Sentence before が	Sentence that comes before が is more important than sentence after it Sentence that comes after は is more important than sentence before it
Information	Old	New	が is like ‘a’ and は is like ‘the’ in English When something is unknown to listener (or speaker), が is used When something is known to both speaker and listener, は can be used Example: 昔、おじいさんがいました。おじさんは優しいです。
Applies to	Full clause	Sub clause	が is valid for the immediate sentence that follows は is valid for the entire sentences that follows
Function	Explanation	Description	が describes a phenomenon or situation は explains about the topic
Scope	No limit	Limited	が has the inherent meaning of excluding what is not denoted by が は does not but is used in comparison

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