B1 Lesson 2: Introduction to Complex Sentences
In the last lesson, we joined two complete sentences to make a compound sentence. Today, we will learn how to write a complex sentence1. This type of sentence is excellent for showing relationships between ideas, like cause and effect, contrast, or time.
Understanding Clauses
To understand complex sentences, you must first understand the two types of clauses.
- Independent Clause: A complete thought. It can be a sentence by itself.
Example: I drank a cup of coffee. - Dependent Clause2: An incomplete thought. It starts with a special word (a subordinating conjunction) and cannot be a sentence by itself.
Example: Because I was tired... (This feels unfinished, right? What happened?)
A complex sentence joins one independent clause with one or more dependent clauses.
The Two Structures of a Complex Sentence
The most important thing to learn is that the punctuation changes depending on the order of the clauses. The words that create dependent clauses include because, although, when, if, while, and since.
Structure 1: Dependent Clause First (Comma Needed)
When the dependent clause comes first, you must use a comma to separate it from the independent clause.
Formula: Dependent Clause , Independent Clause.
Although the traffic was bad, we arrived on time.
(Dependent), (Independent)
Structure 2: Independent Clause First (No Comma Needed)
When the independent clause comes first, you usually do not use a comma.
Formula: Independent Clause + Dependent Clause.
We arrived on time although the traffic was bad.
(Independent) (Dependent)
✍️ B1 Complex Sentence Checklist
- ✔️ Does my sentence have an independent clause and a dependent clause?
- ✔️ Does the dependent clause start with a word like because, although, when, if, etc.?
- ✔️ If the dependent clause comes first, did I use a comma to separate the clauses?
- ✔️ If the independent clause comes first, did I remember not to use a comma?
🧠 Practice Quiz: Comma or No Comma?
Read the sentences below. Decide if they need a comma.
1. When I finish my work I will call you.
Answer: Yes, a comma is needed after "work". (Dependent clause comes first).
2. He didn't go to the party because he was feeling sick.
Answer: No, a comma is not needed. (Independent clause comes first).
3. If you see Mr. Pov please give him this message.
Answer: Yes, a comma is needed after "Pov". (Dependent clause comes first).
📝 Homework: Combine and Create
Get your notebook and pen to practice writing complex sentences.
Part 1: Combine these sentences using the word in brackets. Pay attention to the comma rule.
- He is very rich. He is not happy. (Use 'Although')
- I will make dinner. I get home from work. (Use 'when')
Part 2: Write your own complex sentence to answer the following question.
Why are you learning English? Start your sentence with "Because..."
(Example Answer for Part 2: Because I want to get a better job, I am learning English.)
(Answers for Part 1: 1. Although he is very rich, he is not happy. 2. I will make dinner when I get home from work.)
Vocabulary Glossary
- Complex Sentence: (Noun) - ប្រយោគស្មុគស្មាញ - A sentence with one independent clause and at least one dependent clause. ↩
- Dependent Clause: (Noun Phrase) - ឃ្លាពឹងផ្អែក - A group of words with a subject and verb that cannot stand alone as a sentence. It begins with a subordinating conjunction. ↩
- Independent Clause: (Noun Phrase) - A "complete thought" or simple sentence that can stand alone.
- Subordinating Conjunction: (Noun) - A word that starts a dependent clause (e.g., because, although, when, if).
- Relationship (between ideas): (Noun) - The way in which two or more concepts or ideas are connected.