What's the use of learning English part of speech?

The purpose of parts of speech is that you can't speak English correctly without knowing English.

In other words, I may know many words, but I just don't know why some of them are put in front and some are put behind; Some are in the form of ED, some are in the form of ING; What word to choose in any other situation.

Noun: a word that changes according to the case, indicating a practical or abstract concept;

Verb: a word that is not inflected according to case, but according to tense, voice and number of subjects;

Gerund: a word with both noun and verb properties;

Articles: including today's definite articles and basic guiding words (word guiding clauses);

Pronouns: words that replace nouns or people; Preposition: a word with grammatical function in a sentence;

Adverb: words that modify verbs, adjectives, clauses, sentences or other adverbs without inflectional changes;

Conjunction: a word that connects two sentences or meanings and expresses a logical relationship.

Extended data:

Generally speaking, a sentence consists of two parts, namely, the subject group and the predicate group.

The subject part is generally composed of nouns or gerunds, and the predicate part is generally composed of verbs. For example:

Professor Ward teaches college students English. Ward teaches college students English.

In this sentence, Professor Ward is the subject and the college English teacher is the predicate.

Sentence elements are elements that play a certain role in a sentence. A sentence consists of different sentence components. The components of a sentence include subject, predicate, object, attribute, complement, adverbial, predicative and appositive. Every sentence has a subject, a predicate and an object.