‹ Grammar · Week 4Lesson 27 of 28

Complex Sentences & Sentence Variety

Level B2–C2 · subordination, variety & cohesion

◎What you'll master

Tell an independent clause from a dependent (subordinate) one.
Build all four sentence types: simple, compound, complex, and compound-complex.
Combine short, choppy sentences with subordinating conjunctions and relative clauses.
Vary your sentence openings — subordinate clause, -ing/-ed participle, or adverbial.
Punctuate introductory elements and avoid run-ons, comma splices, and dangling participles.

1Clauses: the building blocks

Every sentence is made of clauses. A clause has a subject and a verb. The difference is whether it can stand alone.

Independent clause

A complete thought that can stand as a sentence on its own.

The lecture ended. · She took careful notes.

Dependent (subordinate) clause

It has a subject and verb but begins with a subordinator (because, although, when, if, since, while…) or a relative pronoun (who, which, that), so it cannot stand alone.

Because the lecture ended. (fragment — needs a main clause)

Because the lecture ended, we left.

2The four sentence types

You combine clauses in four ways. A confident writer uses all four — not just short simple sentences one after another.

Type	Structure	Example
Simple	one independent clause	The results surprised us.
Compound	independent + , and/but/so + independent	The results surprised us, but the method was sound.
Complex	independent + dependent	Although the sample was small, the results surprised us.
Compound-complex	2+ independent + 1+ dependent	Because time was short, we cut the trial, and we published early.

Comma with coordinators

Use a comma before and, but, or, so, yet, for, nor when it joins two full sentences — She revised, and she passed. Don't add one when it only joins two verbs — She revised and passed.

3Combining choppy sentences

A string of short sentences feels flat: The house was old. It stood on the hill. Everyone avoided it. Subordination and relative clauses fuse these into one stronger idea and show how the parts relate.

With a subordinating conjunction

Because it was old, the house on the hill scared everyone.

With a relative clause

The old house, which stood on the hill, was one that everyone avoided.

⚠ Watch out — don't just glue sentences with a comma. The house was old, everyone avoided it. is a comma splice — use a subordinator, a semicolon, or a period instead.

4Varying how you open a sentence

Most weak writing starts every sentence with the subject. Vary the opening to control rhythm and emphasis. Put a comma after an introductory clause or phrase.

Opening with…	Pattern	Example
a subordinate clause	Although / When / Because…, main clause	Although it rained, the match went ahead.
an -ing participle	Walking / Seeing…, main clause	Walking home, she noticed a strange light.
an -ed participle	Built / Exhausted…, main clause	Built in 1920, the house still stands.
an adverbial	In recent years, / Suddenly, / Every morning,…	In recent years, prices have soared.

One idea, three shapes

The team lost, so they trained harder. → Because they lost, the team trained harder. → Having lost, the team trained harder. Same meaning, richer texture.

5Dangling participles — the trap of variety

When a sentence opens with an -ing or -ed phrase, the noun right after the comma must be the one doing that action. If it isn't, the participle dangles.

Walking home, the rain started. (the rain wasn't walking)

Walking home, I felt the rain start. (I was walking)

Built in 1920, we admired the house. → Built in 1920, the house drew our admiration.

⚠ Watch out — always check the subject after the comma. If it can't perform the participle, rewrite so the doer comes first — or turn the phrase into a full clause (As I walked home, the rain started.).

6Run-ons, comma splices & cohesion

Two independent clauses cannot sit together with nothing (a run-on) or with only a comma (a comma splice). Fix them one of four ways.

Fix	Example
period	She studied hard. She passed easily.
comma + coordinator	She studied hard, so she passed easily.
semicolon	She studied hard; she passed easily.
subordinator	Because she studied hard, she passed easily.

Beyond single sentences, cohesion ties ideas together: transitions (however, therefore, for example), pronouns that point back, and a mix of long and short sentences that keeps the reader moving.

Rhythm

End a run of complex sentences with a short one for punch. Variety isn't only grammar — it's pacing.

Practice — 15 questions with instant feedback

0 / 15 correct

Question 1

Which is a complete sentence?______

Question 2

What type is this? 'The train was late, but we still made it.'______

Question 3

Combine with a subordinator: 'It was raining. We stayed in.' → (Because…) it was raining, we stayed in.

Question 4

Which opening is punctuated correctly?______

Question 5

Supply the -ing form: (walk) home, she saw the eclipse.

Question 6

Which avoids a dangling participle?______

Question 7

Supply the -ed form: (build) in 1920, the house still stands.

Question 8

Which fixes the comma splice? 'He was tired, he kept working.'______

Question 9

Add a relative pronoun: The book (…) I borrowed was overdue.

Question 10

Which is compound-complex?______

Question 11

Open with an adverbial: (In recent…) years, sea levels have risen. → supply the missing word:

Question 12

Which sentence uses variety best?______

Question 13

Join as complex: 'She was nervous. She spoke well.' → (Although…) she was nervous, she spoke well.

Question 14

Which best combines: 'The scientist was cautious. Her results were bold. They changed the field.'______

Question 15

Which is the strongest, most-varied revision? 'Technology advances. People adapt. Some resist.'______

✎Fix the Error

Each sentence has one mistake in the underlined word. Type the correction and check.

1.She studied all night, she passed the exam.

2.Walking into the room, the lights were off.

3.The road was icy we drove slowly home.

4.Although the theatre was full.

5.When the bell rang the students left quickly.