How to Make a Compound Sentence Complex

What is a Compound Sentence?

• A compound sentence is made by joining two independent clauses with coordinating conjunctions like and, but, or, so, for, yet.

Example:

• He is poor, but he is honest.
• (Two clauses joined by but.)

What is a Complex Sentence?

• A complex sentence has one main clause and one or more subordinate (dependent) clauses. These are joined by subordinating conjunctions like because, although, since, when, while, if, though, as, unless, etc.

Example:

• Although he is poor, he is honest.

Now, let's learn some rules for changing compound sentences into complex ones.

1. Clause + and + Clause → When/While/As

🔁 Change:

• Replace "and" with "when", "while", or "as" (for actions happening together)
• Use this when two actions happen at the same time.

🔁 Structure:

• Clause + and + Clause → When/While/As + one clause, main clause

Examples:

1. He took a bath, and he got ready for school.

👉 When he took a bath, he got ready for school.

2. The teacher entered, and the students stood up.

👉 When the teacher entered, the students stood up.

3. She was reading, and I was writing.

👉 While she was reading, I was writing.

4. He was cooking, and I was cleaning.

👉 As he was cooking, I was cleaning.

5. They arrived, and we welcomed them.

👉 When they arrived, we welcomed them.

Exercise for Practice

Change each compound sentence into a complex sentence.

1. She opened the book, and she started reading.
2. The clock struck twelve, and the bell rang.
3. I reached the station, and the train arrived.
4. He sat down, and he began to write.
5. The sun rose, and the birds started chirping.
6. I went to the kitchen, and I made tea.
7. He took the phone, and he called his friend.
8. She saw the cat, and she ran away.
9. We entered the hall, and the show started.
10. The children shouted, and the teacher came in.

2. Clause + but + Clause → Although / Though / Even though

• Replace "but" with "although", "though", or "even though" (to show contrast)
• Use this when the second clause shows contrast to the first one.

🔁 Structure:

• Clause + but + Clause → Although/Though + one clause, main clause

Examples:

1. He is poor, but he is honest.

👉 Although he is poor, he is honest.

2. She was tired, but she finished the work.

👉 Though she was tired, she finished the work.

3. It was raining, but they went out.

👉 Even though it was raining, they went out.

4. He is weak, but he plays well.

👉 Though he is weak, he plays well.

5. I didn’t study, but I passed the exam.

👉 Although I didn’t study, I passed the exam.

Exercise for Practice

Change each compound sentence into a complex sentence.

1. She is rich, but she is not proud.
2. He was late, but he joined the meeting.
3. I was scared, but I went in.
4. It was cold, but they went swimming.
5. He didn’t study, but he passed the exam.
6. The road was long, but we walked.
7. She is young, but she is wise.
8. He was sick, but he went to work.
9. I lost the game, but I was happy.
10. They failed, but they did not give up.

3. Clause + so + Clause → Because/Since

• Replace "and or so" with "so that", "because", or "as" (to show cause or reason)
• Use this when the second part shows the result of the first action.

🔁 Structure:

• Clause + so + Clause → So that + clause or Because/Since + reason clause

Examples:

1. He studied hard, so he passed the test.

👉 Because he studied hard, he passed the test.

2. She saved money, so she could buy a phone.

👉 She saved money so that she could buy a phone.

3. It was late, so we went home.

👉 As it was late, we went home.

4. I was hungry, so I ate some food.

👉 Since I was hungry, I ate some food.

5. He worked hard, so he succeeded.

👉 Because he worked hard, he succeeded.

Exercise for Practice

Change each compound sentence into a complex sentence.

1. He studied hard, so he got good marks.
2. It rained heavily, so we stayed inside.
3. I woke up early, so I reached on time.
4. The dog barked, so I looked outside.
5. He ran fast, so he won the race.
6. She worked late, so she missed dinner.
7. They built a dam, so they could store water.
8. I saved money, so that I could buy a bicycle.
9. The teacher explained well, so we understood.
10. The power went out, so we lit candles.

4. Clause + or + Clause → If/Unless + clause, main clause

• Replace "or" with "if" or "unless" (to show condition)
• Use this when the first clause is the condition of the second clause.

🔁 Structure:

• Clause + or + Clause → If/Unless + clause, main clause

Examples:

1. Work hard, or you will fail.

👉 If you don’t work hard, you will fail.

2. Hurry up, or you will miss the train.

👉 If you don’t hurry up, you will miss the train.

3. Obey me, or you will be punished.

👉 Unless you obey me, you will be punished.

4. Study well, or you won’t pass.

👉 If you don’t study well, you won’t pass.

5. Take rest, or you will fall sick.

👉 If you don’t take rest, you will fall sick.

Exercise for Practice

Change each compound sentence into a complex sentence.

1. Study now, or you will regret later.
2. Be careful, or you will break it.
3. Eat quickly, or your food will get cold.
4. Follow the rules, or you will be punished.
5. Wear a coat, or you’ll catch a cold.
6. Hurry up, or we will be late.
7. Pay attention, or you’ll make mistakes.
8. Try again, or you’ll never learn.
9. Help me, or I can’t finish it.
10. Don’t waste time, or you’ll fail.

5. Clause + for + Clause → Because/Since + reason clause

🔁 Change:

• Replace "for" with "because" or "since" (to show reason)
• Use this when the second clause gives the reason for the first.

🔁 Structure:

• Clause + for + Clause → Because/Since + reason clause

Examples:

1. He was happy, for he had won the prize.

👉 He was happy because he had won the prize.

2. I did not go out, for it was raining.

👉 I did not go out because it was raining.

3. She was sad, for her pet was lost.

👉 She was sad since her pet was lost.

4. He stayed home, for he was sick.

👉 He stayed home because he was sick.

5. They cheered, for their team won.

👉 They cheered because their team won.

Exercise for Practice

Change each compound sentence into a complex sentence.

1. I cannot eat, for I am not hungry.
2. They stayed inside, for it was stormy.
3. He looks tired, for he has worked all day.
4. She didn’t come, for she was busy.
5. I left early, for I had a meeting.
6. The teacher was angry, for the students were noisy.
7. She was happy, for she won the prize.
8. I missed the show, for I was out of town.
9. They were excited, for the match had begun.
10. He got a prize, for he did well in class.

Summary Table

✅ Practice Tip

• Try changing the following compound sentences into complex sentences using these rules. It will help you understand the structure and improve your grammar!

Exercise in Action [Grade 9 & 10]

Transform the following sentences as directed in brackets. Also explain how to make such sentences simple.

1. Compound Sentences with ‘but’

1. He was very poor but honest. (Complex) 
2. He caught the thief but didn’t punish him. (Complex)
3. It was a beautiful place but there were a lot a problems (Complex)
4. He was very poor but honest. (Complex) 
5. He caught the thief but didn’t punish him. (Complex)
6. It gives pleasure but we cannot get freedom to use it. (Complex)
7. The river destroys the houses of men but it is still very useful to us. (Complex)
8. Mr. Rahim is not only punctual but also sincere. (Complex)

2. Compound Sentences with ‘or’

1. Use it or you cannot keep pace with the modern world. (Complex)
2. Read attentively or you will fail in the exam.  (Complex)
3. Use it or you cannot keep pace with the modern world. (Complex)
4. Read attentively or you will fail in the exam.  (Complex)

3. Compound Sentences with ‘and’

1. The bear went away and he escaped himself. (Complex)
2. He came to a house and asked for something to eat. (Complex)
3. Scientists spent many years and worked hard to invent television. (Complex)
4. He lay down on the ground and feigned death. (Complex)
5. The bear went away and he escaped himself. (Complex)
6. So, he collected his things and went to live by himself. (Complex)
7. They fought bravely and snatched the red sun of independence. (Complex)
8. He came to a house and asked for something to eat. (Complex)
9. A man has an Internet connection and gets a link soon according to his expectation. (Complex) 
10. In youth mind is soft and it can be shaped easily. (Complex)
11. There is class distinction in a train and people can buy tickets of various classes. (Complex)
12. A man has an internet connection and gets a link soon. (Complex)