Mastering It-Cleft Sentences: Agreement and Adverbials
It-cleft sentences are powerful structures used to emphasize a specific part of a sentence, typically following the pattern It + be + emphasized element + that/who clause. For example, instead of saying "I lost my keys," you can emphasize the subject by saying, "It was I who lost my keys," or emphasize the timing by saying, "It was not until yesterday that I found them."
This advanced challenge tests the tricky grammatical nuances of cleft sentences. You will navigate complex pronoun and verb agreement rules (e.g., knowing why It is I who am is correct), properly emphasize prepositional phrases (It was to the Duchess that), and structure adverbial and negative time clauses (It was only after... that). You'll also encounter cleft sentences combined with modal verbs of deduction (It must have been... that).
The 10 questions in this challenge feature a mix of single-choice, multi-choice, drop-down, and drag-and-drop formats to thoroughly test your advanced syntax skills.
Try the quiz to check your knowledge!
The correct answers are It was because the lead actor forgot his lines that the audience started laughing. and It was the collapsing scenery, rather than the bad acting, that ultimately ruined the show.
It-clefts use that to connect the emphasized focus to the rest of the sentence.
Even when emphasizing a reason ("because..."), you must use that, not why. Similarly, what is never used as the relative pronoun in a standard it-cleft sentence (though it is used in wh-clefts, such as "What ruined the show was the scenery").
The correct answers are It, am, and have.
Cleft sentences must always begin with the dummy pronoun it, regardless of whether the emphasized noun is singular or plural.
In formal English, when the emphasized part is a subject pronoun ("I", "you"), the verb in the relative clause must agree with that specific pronoun. Therefore, the relative pronoun "who" takes am to agree with "I", and have to agree with "you".
The correct answers are It is I who am taking full responsibility for the incident. and It was the marketing team that left the milk out overnight.
In formal it-cleft sentences, the verb in the relative clause must agree with the emphasized subject. Because the subject is I, the correct verb is am (not is).
Furthermore, when the emphasized noun phrase functions as the subject of the relative clause (the marketing team left the milk out), you must use that or who, never the object pronoun whom.
Help the kingdom's chief gossipmonger set the record straight about the latest royal scandal.
The rumors claim the King gave the dragon to the Duke, but it was actually _____ he gifted the fire-breathing beast!
The correct answer is to the Duchess that.
In a cleft sentence, if the original verb requires a preposition (e.g., "gifted [something] to [someone]"), that preposition must either stay at the end of the relative clause or move with the focused noun.
Because the sentence ends with "he gifted the fire-breathing beast!" (missing the preposition "to"), the preposition must be included in the focus: It was to the Duchess. When a prepositional phrase is the focus of a cleft sentence, we use that to introduce the relative clause.
The correct answers are It was not until midnight that the thief bypassed the security cameras. and It was from the hidden safe that the diamond was actually stolen.
In an it-cleft sentence emphasizing a prepositional phrase (like from the hidden safe), the relative clause must be introduced by that, not where or when.
Additionally, the distractor "did the thief bypass" incorrectly mixes an it-cleft with negative inversion. You can either use an it-cleft ("It was not until midnight that the thief bypassed...") or negative inversion ("Not until midnight did the thief bypass..."), but never both at the same time!
Complete the dramatic chef's explanation of a culinary disaster by dragging the correct words into the blanks.
"It was because the main oven suddenly malfunctioned that the delicate cheese soufflé collapsed. Furthermore, it was to my senior assistant that I had explicitly handed the timer, so he is entirely to blame!"
"It was because the main oven suddenly malfunctioned that the delicate cheese soufflé collapsed. Furthermore, it was to my senior assistant that I had explicitly handed the timer, so he is entirely to blame!"
was: This forms the standard "It was... that" cleft structure in the past tense.
that: When focusing on an entire "because" clause in an it-cleft, the clause must be followed by "that". Many learners incorrectly use "why" here.
to: We "hand something to someone." In a cleft sentence, the preposition stays with the noun phrase when it is moved into the focus position (It was to my assistant that...).
Complete Dr. Aris's dramatic lab journal entry about his recent mishap.
It was not until the purple smoke filled the entire laboratory _____ realized I had mixed up the baking soda and the highly reactive unobtainium.
The correct answer is that I.
In an it-cleft sentence focusing on a time phrase (especially with "not until"), the relative clause must be introduced by that.
While "when" might sound tempting because it refers to time, cleft sentences rely on "that" to connect the focused element to the rest of the clause. "Did I" would only be used if the sentence started with negative inversion (Not until the smoke filled the lab did I realize...).
The correct answers are must have been and that.
In an it-cleft sentence, we use the relative pronoun that (not where or which) to connect the emphasized phrase to the rest of the sentence, even when emphasizing a prepositional phrase of place like "through the open skylight."
Additionally, must have been is the correct modal perfect form to express a strong logical deduction about a past event.
Help the theatrical ghost hunter complete her spooky field report by dragging the correct words into the blanks.
"It was only after the candles mysteriously blew out that the phantom finally made its presence known. Furthermore, it was the skeptical cameraman, not the psychic, who fainted first!"
"It was only after the candles mysteriously blew out that the phantom finally made its presence known. Furthermore, it was the skeptical cameraman, not the psychic, who fainted first!"
was: The past tense "was" is required to match the past tense verbs in the rest of the sentence ("blew out", "made", "fainted").
that: In an it-cleft sentence focusing on an adverbial time phrase, we must use the relative pronoun "that" to connect the clauses. Using "when" is a very common mistake!
who: The cameraman is the subject of the verb "fainted," so the subject relative pronoun "who" is correct.
Complete the project manager's slightly accusatory email regarding the disastrous new company mascot.
Please stop blaming the marketing interns; it is I who _____ responsible for approving the giant neon platypus.
The correct answer is am.
In an it-cleft sentence where the focused element is a subject pronoun ("I"), the verb in the relative clause must agree with that pronoun.
Even though "who is" sounds very natural in casual speech, formal grammar requires the verb to match "I" (I am -> It is I who am).
Clause
A clause is a grammatical unit built around a verb — typically a subject plus a predicate (She laughed; The manager approved the budget). Clauses come in two types: independent clauses stand alone as complete sentences; dependent clauses need an independent clause to make sense (Because I overslept — incomplete on its own).
Spotting clause boundaries is the foundation of correct punctuation. Once you can see where one clause ends and another begins, comma rules, run-on sentences, and complex sentence structure stop being mysteries.
Complex sentence
A complex sentence combines an independent clause with at least one dependent (subordinate) clause: I missed the bus because I overslept. The dependent clause adds extra information — usually about time, reason, condition, or which thing is meant — but can't stand alone. It's introduced by a subordinating conjunction (because, although, if, when, while) or a relative pronoun (who, which, that).
Mastering complex sentences is the move from simple, choppy writing to prose that links ideas. It's also where comma decisions get interesting — placement depends on which clause comes first.
Inversion
Inversion is reversing the normal English word order of subject + verb. The everyday case is subject–auxiliary inversion for questions: Sam has read it → Has Sam read it?. The more advanced case is inversion after fronted negative or restrictive expressions: Rarely have I seen such dedication / Not only does she sing, she also writes.
The advanced kind is a hallmark of formal and literary English — used after openers like never, seldom, not until, only when, little did I know. Mastering it is a C1+ skill that signals careful, register-appropriate writing.
Modal verb
A modal verb is a special class of auxiliary — can, could, may, might, must, shall, should, will, would — that adds shades of meaning around possibility, ability, permission, obligation, or speculation. I can swim (ability), You should rest (advice), It might rain (possibility), You must leave (obligation).
Modals are grammatically peculiar: no -s in the third person (she can, not she cans), no infinitive, no participle, followed by the bare verb (I can swim, never I can to swim). Mastering them is the move from describing facts to expressing how you feel about them — likelihood, necessity, recommendation.
Negation
Negation in English usually places not after the auxiliary or modal verb: I am not going, She does not know, You must not go. When there's no auxiliary, you add do-support: I go → I do not go. Most combinations contract: don't, can't, won't, isn't.
The trickiest rule for many learners: double negatives are not standard English. I didn't see nothing is non-standard; the standard forms are I saw nothing or I didn't see anything. Negative words like never, nobody, nothing already carry the negation — adding not on top doubles up.
Past tense
The past tense is how English talks about events finished before now. It comes in four flavours: simple past (I walked) for completed events, past progressive (I was walking) for actions ongoing at a past time, past perfect (I had walked) for events before another past event, and past perfect progressive (I had been walking) for ongoing events leading up to a past point.
Choosing the right one is what makes past narratives clear instead of murky. When I arrived, she ate dinner is technically grammatical but means something different than had eaten (already done) or was eating (in progress when you arrived).
Phrase
In grammar, a phrase is a group of words (sometimes a single word) that functions as a single unit in a sentence — but doesn't include a subject + verb pair the way a clause does. Common types: noun phrase (the old red car), verb phrase (has been running), prepositional phrase (on the table), adjective phrase (incredibly tired), adverb phrase (very quickly).
Phrases are the building blocks between individual words and full clauses. Recognising them helps you see how sentences hold together — and where you can break, expand, or rearrange them without losing meaning.
Preposition
A preposition is a small word that links a noun or noun phrase to other parts of the sentence — usually marking time, place, or relationship: in, on, at, to, from, with, over, under, between, during. The book on the table, We met at noon, She lives in Berlin.
Prepositions are deceptively small. Their meaning shifts dramatically by collocation (depend on, good at, afraid of), and their choice rarely translates directly between languages. Picking the right preposition is one of the trickiest, most idiomatic-sounding parts of English.
Pronoun
A pronoun is a small, closed class of words that stands in for a noun or noun phrase. The main types: personal (I, you, he, she, it, we, they) plus their object (me, him) and possessive (my, mine) forms; demonstrative (this, that); relative (who, which, that); interrogative (who, what); and reflexive (myself, yourself).
Pronouns are how English avoids endlessly repeating names. The catch: their meaning depends entirely on context, so unclear pronoun reference (Tom told Mike that he was wrong — who's he?) is one of the most common writing problems.
Relative clause
A relative clause is a dependent clause that modifies a noun, typically introduced by a relative pronoun (who, whom, whose, which, that) or relative adverb (where, when, why). The man who lives in this house has not been seen for days. They split into restrictive (essential to the meaning, no commas) and non-restrictive (extra information, set off by commas).
The split matters because the comma changes the meaning: My brother who lives in Paris (one of several brothers) vs. My brother, who lives in Paris, (my only brother). Getting comma placement right is one of the highest-leverage moves at B2+.
Sentence
A sentence is the largest grammatical unit in writing — one or more clauses expressing a complete thought, ending with a period, question mark, or exclamation mark. English sentences come in four structural types: simple (one independent clause), compound (two or more independent clauses joined), complex (independent + dependent clause), and compound-complex (multiple independent + dependent clauses).
Mastering sentence types is what lets you vary rhythm in writing. All-simple sentences read as choppy; all-complex sentences read as dense. Mixing them is what makes prose breathe.
Subject
The subject is the part of a sentence or clause that tells you who or what the sentence is about. It's typically a noun, pronoun, or noun phrase that comes before the verb and controls the verb's form: She works (singular) vs They work (plural).
The subject isn't always the doer of the action — in passive sentences, it receives the action (The window was broken). English also uses dummy subjects like it and there that hold the subject slot without carrying real meaning (It is raining; There are problems). Spotting the real subject is what makes subject-verb agreement automatic.
Verb
A verb is a word that expresses an action, a state, or an occurrence — the engine of every English sentence. Most verbs have five forms: base (go), -s form (goes), past tense (went), past participle (gone), and -ing form (going). The verb be is the major exception with eight forms; modal verbs like can and must have fewer.
Verbs carry tense (when), aspect (how it unfolds), mood (the speaker's attitude), and voice (active vs passive). Mastering them is foundational — virtually every other grammar topic depends on getting verbs right.
Perfect tense
The perfect aspect marks an action as complete relative to a point in time. It's formed with have + past participle: I have eaten (present perfect), She had finished (past perfect), They will have arrived (future perfect). The perfect doesn't just say when — it says the action's completion is relevant to the time of reference.
The trickiest English-specific use is the present perfect: I have lived in Paris connects the past to now (you may still live there), while I lived in Paris doesn't. This connection is one of the biggest jumps for learners whose native language doesn't make the same distinction.
Word Order
Word order is the sequence in which words appear in a sentence. English is fundamentally an SVO language — subject, verb, object (Kate loves Mark). The order of adjectives, adverbs, and modifiers within a noun phrase also follows fixed patterns (a small red wooden box, not a wooden red small box).
In English, word order carries grammatical meaning — change the order and you change the sentence. The dog bit the man and The man bit the dog differ only in word order, but the meaning flips entirely.
C1 | Advanced
C1 is the advanced level in the CEFR framework, sitting between B2 and C2. At C1 you stop translating in your head and start thinking in English — handling specialised articles outside your field, picking up implicit meaning, and writing structured arguments on complex topics.
Grammatically, C1 means natural use of inversion (Rarely have I seen…), mixed and advanced conditionals, subjunctive forms in formal contexts, and cleft sentences for emphasis. Most university programmes for non-native speakers and many professional certifications set C1 as their entry standard.
Difficulty: Hard
The Hard difficulty tag marks questions and challenges aimed at upper-intermediate to advanced learners — typically B2 and above. Expect interacting rules, edge cases, distractors that look right at first glance, and contexts where the surface meaning and the grammatical answer don't match.
Filter by Hard when you're past the basics and want material that genuinely tests your understanding. These questions catch the gaps your textbook didn't — register-sensitive choices, exception cases, mixed conditionals, the difference between would have been and had been.