Every sentence follows a pattern. This is what makes it grammatically correct.

Before we can understand sentence patterns, we need to know what the different parts of a sentence are.
1. Subject (S): The subject is sometimes called the naming part of a sentence. The subject shows what the sentence is about or who or what performs the action.
Ramu built a house.
In this sentence, 'Ramu' is the Subject (S).
2. Verb (V): Verbs are the action words in a sentence. Verbs describe what the subject is doing. Verbs include words like 'love', 'agree', 'feel', 'am' and 'have'.
Ramu built a house.
In this sentence, 'built' is the Verb (V).
 3. Direct Object (DO): The Direct Object in a sentence is the entity that is acted upon by the subject
Ramu built a house.
In this sentence, 'a house' is the Direct Object (DO).
4. Indirect Object (IO): The Indirect Object gives information about towhom/what or for whom/what the action was made. The Indirect Object only follows the Direct Object.
Ramu built a house for Janu.
Here, 'Janu' is the Indirect Object (IO).
5. Complement (C): It's a word, clause, or phrase that's needed to complete a given expression.
Every child is a gift.
In this sentence, 'gift' is the Complement (C).
 Types of complement: There are two main types of complements: Subject and object complement. Subject complement has to do with the subject of a sentence and object complements with the object.
i) Subject complement: The subject of a sentence is the person, place, thing or idea. Subject complements follow linking verbs only (not action verbs). Linking verbs are forms of the verb "to be". Linking verbs include am, is, are, was, and were. While "to be" verbs are always linking verbs, you also have verbs that can act as action verbs or linking verbs, depending on the sentence. Example: grow, look, sound, smell, and taste.
Subject complement can be a noun, an adjective, a single word, or a group of words that act as a noun or adjective. Subject complements can be further broken down into predicate nominatives and predicate adjectives.
 Predicate nominatives: Predicate nominatives effectively "rename" the subject in the sentence, answering who they are in the form of another noun.
  • I am a singer. (Providing more information about "I").
  • They were workers there. (Providing more information about "they").
 Predicate adjectives:  Whereas predicate nominatives rename the subject, predicate adjectives describe or modify the subject the way an adjective would.
  • Aira looked frustrated. (Providing more information about Aira).
  • She seemed honest. (Providing more information about "She").
  • He appears handsome. (Providing more information about "He").
Subject Complements vs Objects: Linking verbs have subject complements. Action verbs have direct objects. An object will answer the question "who" or "what" in reference to the verb. A complement will provide greater detail about the subject.
  • She ate the burger.
"the burger" is an object. It's answering the question "who" or "what" is being eaten. As such, it's following an action verb and receiving the action of the verb "ate".
  • He jumped high.
"high" is a subject complement. It's not answering the question "who" or "what" and it's not receiving the action of the verb "high". Rather, it's providing more detail about the subject "he". Now we know he's jumped higher.
ii) Object complements:  The object of a sentence is the person, place, thing or idea that's receiving the action of the verb.
He bakes Barbie cakes.
Barbie cakes is the object. It's receiving the action of the linking verb "bakes". It answers the question "who" or "what".
Object complements follow linking verbs as well. However, they provide more information about the object. So, while the object of the sentence receives the action of the verb, object complements can beef up, or complement, those objects. Object complements can also be a noun, an adjective, a single word, or a group of words that act as a noun or adjective.
  • He makes me very comfortable. (Providing more information about the object "me").
  • A cotton top will keep your body very cool in the summer. (Providing more information about the object "your body").
6. Adverbial / Adjunct (A): The adverbial/adjunct is an optional part of a sentence. That means it will not affect the remainder of the sentence if it is not mentioned.
Thomas helped Sampath in the Nehru stadium.
In this sentence, 'in the Nehru stadium' is the Adverbial/Adjunct (A).