Create a correct sentence.
So full was the train that commuters had to stand all the way.
Starting a sentence with So full creates an adverbial clause of result. Using so+adjective means you invert the position of verb and subject: So full was the train. The second part of the sentence is the independent clause and follows the normal word order ... commuters had to stand all the way
Adverb
An adverb is a word that modifies a verb, adjective, determiner, clause, preposition, or sentence. Adverbs typically express manner, place, time, frequency, degree, level of certainty, etc., answering questions such as how?, in what way?, when?, where?, and to what extent?. This function is called the adverbial function, and may be realized by single words (adverbs) or by multi-word expressions (adverbial phrases and adverbial clauses).
Adverbs are traditionally regarded as one of the parts of speech. However, modern linguists note that the term "adverb" has come to be used as a kind of "catch-all" category, used to classify words with various different types of syntactic behavior, not necessarily having much in common except that they do not fit into any of the other available categories (noun, adjective, preposition, etc.)
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.
Dependent Clause
A dependent clause is a clause that provides a sentence element with additional information, but which cannot stand alone as a sentence. A dependent clause can either modify an adjacent clause or serve as a component of an independent clause. Some grammarians use the term subordinate clause to refer only to adverbial dependent clauses.
The different types of dependent clauses include content clauses (noun clauses), relative (adjectival) clauses, and adverbial clauses.
In Indo-European languages, a dependent clause usually begins with a dependent word. One kind of dependent word is a subordinating conjunction. Subordinating conjunctions are used to begin dependent clauses known as adverbial clauses, which serve as adverbs.
In the following examples, the adverbial clauses are bold and the subordinating conjunctions are italicized:
- Wherever she goes, she leaves her luggage (The adverbial clause wherever she goes modifies the verb leaves.)
- Bob enjoyed the movie more than I did. (The adverbial clause than I did modifies the adverb more.)
A subordinating conjunction can also introduce a noun clause:
- I know that he likes me. (The noun clause that he likes me serves as the object of the main-clause verb know.)
Another type of dependent word is the relative pronoun. Relative pronouns begin dependent clauses known as relative clauses; these are adjective clauses, because they modify nouns. In the following example, the relative clause is bold and the relative pronoun is italicized:
- The only one of the seven dwarfs who does not have a beard is Dopey. (The adjective clause who does not have a beard describes the pronoun one.)
A relative adverb plays the part of an adverb in a relative clause, as in
- That is the reason why I came. (The relative clause why I came describes the noun reason, and within the relative clause the adverb why modifies the verb came.)
- That is the place where he lives. (The relative clause where he lives describes the noun place, and within the relative clause the adverb where modifies the verb lives.)
An interrogative word can serve as an adverb in a noun clause, as in
- No one understands why you need experience. (The noun clause why you need experience functions as the direct object of the main-clause verb "understands", and within the noun clause why serves as an adverb modifying need.)
Clause
A clause is a grammatical unit built around a verb that typically contains a subject and a predicate. Understanding clauses is essential because they are the core building blocks of every sentence you read, write, or speak.
What makes a clause?
At minimum, a clause needs a verb (the predicate) and, in most cases, a subject — the person or thing the verb says something about. The predicate can also include objects, complements, and modifiers.
- She laughed. — subject (she) + verb (laughed)
- The manager approved the budget yesterday. — subject + verb + object + modifier
Sometimes the subject is left out. This happens regularly in imperative sentences and non-finite clauses:
- Sit down. — no visible subject, but "you" is understood
- Walking home, I noticed the shop was closed. — the -ing clause has no stated subject
Types of clauses
There are two main types:
-
Independent clause (also called a main clause) — can stand on its own as a complete sentence. It contains a finite verb.
- I missed the bus.
-
Dependent clause (also called a subordinate clause) — cannot stand alone and needs an independent clause to make sense.
- Because I overslept — incomplete on its own
Combine them and you get a complex sentence:
- I missed the bus because I overslept.
A simple sentence has one independent clause. More complex sentences combine independent and dependent clauses in various ways.
Quick check: If you can remove a group of words from a sentence and it still has a subject + finite verb and makes sense on its own, that group is likely an independent clause.
Why clauses matter
Recognizing clause boundaries helps you punctuate correctly, avoid run-on sentences, and build more varied, natural-sounding writing. Once you can spot where one clause ends and another begins, sentence structure becomes much easier to manage.
Ready to practice? Try Complex Sentence for the basics, then move on to Complex Sentence: Adverbials or Participle Clauses: Shortening Sentences with -ing and Having + Past Participle to deepen your skills.
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.