Complex Sentence

A complex sentence has one or more dependent clauses (also called subordinate clauses). Since a dependent clause cannot stand on its own as a sentence, complex sentences must also have at least one independent clause. In short, a sentence with one or more dependent clauses and at least one independent clause is a complex sentence.

A sentence with two or more independent clauses plus one or more dependent clauses is called compound-complex or complex-compound.

In addition to a subject and a verb, dependent clauses contain a subordinating conjunction or similar word. There are a large number of subordinating conjunctions in English. Some of these give the clause an adverbial function, specifying time, place, or manner. Such clauses are called adverbial clauses.

When I stepped out into the bright sunlight, from the darkness of the movie house, I had only two things on my mind. (S. E. Hinton, The Outsiders))
This complex sentence contains an adverbial clause, When I stepped out into the bright sunlight from the darkness of the movie house. The adverbial clause describes when the action of the main clause, I had only two things on my mind, took place. A relative clause is a dependent clause that modifies a noun or noun phrase in the independent clause. In other words, the relative clause functions similar to an adjective.

• Let him who has been deceived complain. (Miguel de Cervantes, Don Quixote)
• You, who have never known your family, see them standing around you. (J.K. Rowling, Harry Potter and the Sorcerer's Stone)

A noun clause is a dependent clause that functions like a noun.

In the first example, the restrictive relative clause who has been deceived specifies or defines the meaning of him in the independent clause, Let him complain.

In the second example, the non-restrictive relative clause who have never known your family describes you in the independent clause, You see them standing around you.

A noun clause may function as the subject of a clause, or as a predicate nominative or an object.
What she had realised was that love was that moment when your heart was about to burst. (Stieg Larsson, The Girl with the Dragon Tattoo)
In this sentence the independent clause contains two noun clauses.
The noun clause What she had realized serves as the subject of the verb was, and that love was that moment serves as complement. The sentence also contains a relative clause, when your heart was about to burst.

C1 | Advanced

C1 is the fifth of six levels in the Common European Framework of Reference for Languages (CEFR), sitting between B2 (Upper-Intermediate) and C2 (Proficiency). It's classified as Advanced — the stage where you stop translating in your head and start thinking in English.

What a C1 user can do

At this level, you're expected to handle complex, demanding language across a wide range of situations:

• Reading — You can understand long, complex texts, including specialized articles and technical instructions outside your own field. You pick up on implicit meaning, not just what's stated directly.
• Speaking — You express yourself fluently and spontaneously with minimal searching for words. You use language flexibly for social, academic, and professional purposes.
• Writing — You produce clear, well-structured, detailed text on complex subjects, with controlled use of organizational patterns, connectors, and cohesive devices.
• Listening — You follow extended speech even when it isn't clearly structured or when relationships between ideas are only implied.

What C1 grammar looks like

C1-level grammar goes well beyond accuracy with tenses and articles. You're expected to use advanced structures naturally, including:

• Inversion for emphasis (Rarely have I seen such dedication.)
• Mixed and advanced conditionals (Had she known, she would never have agreed.)
• Subjunctive forms in formal contexts (It's essential that he be informed.)
• Cleft sentences for focus (What concerns me is the timeline.)
• Complex noun phrases and nominalization (The government's repeated failure to act…)

The difference between B2 and C1 isn't just knowing these structures exist — it's using them appropriately and with control across different registers.

Self-check: If you can read an opinion piece in The Guardian or The Economist and follow the argument without a dictionary, and if you can write a structured response disagreeing with it, you're likely operating at C1.

How C1 fits in the CEFR scale

The CEFR has six levels: A1 → A2 → B1 → B2 → C1 → C2. C1 is where most universities and professional bodies set their language requirements for non-native speakers.

Ready to test yourself? Try Pass the Test to Determine Your English CEFR Level or go straight to the C1/C2-level test. You can also practice key C1 structures like Inversion and Conditional Subjunctive.

Difficulty: Medium

Medium difficulty. Difficulty levels represent author's opinion about how hard a question or challenge is.