Still confused about subject, object, and complement—can someone explain with simple examples?

Question

I'm reviewing some English grammar rules and keep getting confused between subject, object, and complement in sentences. For example, in the sentence "She is a teacher," I don't know if 'a teacher' is the object or a complement. Then in "He reads a book," I think 'a book' is the object, but I'm not sure how to spot complements in other sentences.

Sometimes I also see sentences like "They elected him president"—and I'm not sure what 'president' is in that structure. Could someone explain the difference between subject, object, and complement with easy examples? I'm studying for an English writing exam, so clear explanations would really help!

Context:
Preparing for an ESL writing test (academic English, intermediate level)

Coach Lee · Accepted Answer

Understanding Subjects, Objects, and Complements by Pattern Here's a practical pattern you can use: Subject: Who or what the sentence is about (usually does the action) Verb: The action or state Object: Receives the action (answers 'what?' or 'whom?' after the verb) Complement: Renames or describes the subject (after linking verbs like 'be', 'become', 'seem') Example 1: "The students wrote letters." The students (subject) wrote (verb) letters (object) Why? Ask: What did the students write? Letters (object) Example 2: "My father is an engineer." My father (subject) is (linking verb) an engineer (complement) Why? 'An engineer' gives more information about 'My father', linked by the verb 'is'. To Practice: Identify subject, verb, object, and complement in these sentences: The cat chased the mouse. The weather became colder. Self-check tip: If the verb is an action, look for an object. If it is a 'be' or linking verb, look for a complement telling more about the subject. Correction Step: If you see 'is', 'are', 'seem', or 'become', the next noun/adjective is likely a complement, not an object.

Nora Grammar · Answer

Compare and Contrast: Spotting Objects vs. Complements Let’s look at similar sentences to see the difference between an object (action receiver) and a complement (extra subject info): Example A: "Lisa painted the door." Lisa (subject) painted (verb) the door (object: receives the action) Example B: "Lisa is talented." Lisa (subject) is (linking verb) talented (complement: describes 'Lisa') Key difference: If the verb is an action (like 'painted'), the following noun is usually an object. If the verb is a linking verb (like 'is', 'become', 'seems'), the following word describes or renames the subject—it is a complement. Quick Exercise: Try writing two sentences—one with an action verb and object, and another with a linking verb and complement. Swap the verbs to see how the sentence changes! Correction advice: Ask yourself: “Is this word [after the verb] getting the action, or is it telling me more about the subject?”

Jin Park · Answer

Clarifying Sentence Parts by Role Every sentence part has a job: Subject: The 'doer' or main topic Object: What gets the action Complement: Gives extra info or identity to the subject (after linking verbs) Let's see how this works: Sentence 1: "John considers Sarah helpful." Subject: John (the 'doer') Object: Sarah (receives the consideration) Complement: helpful (describes Sarah—so this is called an 'object complement') Sentence 2: "My coffee tasted bitter." Subject: My coffee Verb: tasted (linking verb) Complement: bitter (describes 'my coffee') (No object, because 'tasted' is not acting on something else.) Try-it-yourself: Find a news headline. Identify the subject, then ask if something acts on someone/thing (object) or simply describes the subject (complement). Correction tip: Complements follow linking verbs and link back to the subject/object, not the verb's action. Objects follow action verbs and receive action directly.

Still confused about subject, object, and complement—can someone explain with simple examples?

What to Know

3 Answers

Question You Likely Still Have	Direct Answer	How To Apply It
What is the core rule for still confused subject object?	Understanding Subjects, Objects, and Complements by Pattern Here's a practical pattern you can use: Subject: Who or what the sentence is about (usually does the action) Verb: The action or state Object: Receives the action (answers 'what?' or 'whom?' after the verb) Complement: Renames or describes the subject (after linking verbs like 'be', 'become', 'seem') Example 1: "The students wrote letters." The students (subject) wrote (verb) letters (object) Why?	Letters (object) Example 2: "My father is an engineer." My father (subject) is (linking verb) an engineer (complement) Why?
How do I apply still confused subject object in a sentence like mine?	To Practice: Identify subject, verb, object, and complement in these sentences: The cat chased the mouse.	Complements Let’s look at similar sentences to see the difference between an object (action receiver) and a complement (extra subject info): Example A: "Lisa painted the door." Lisa (subject) painted (verb) the door (object: receives the action) Example B: "Lisa is talented." Lisa (subject) is (linking verb) talented (complement: describes 'Lisa') Key difference: If the verb is an action (like 'painted'), the following noun is usually an object.
What mistakes should I avoid with still confused subject object?	Letters (object) Example 2: "My father is an engineer." My father (subject) is (linking verb) an engineer (complement) Why?	Correction Step: If you see 'is', 'are', 'seem', or 'become', the next noun/adjective is likely a complement, not an object.