Wh-Cleft Sentences: Standard, Reversed, and Action Focus
Wh-cleft sentences are advanced grammatical structures used to place emphasis on a specific part of a sentence. Instead of simply saying, "I need a vacation," you can add dramatic focus by saying, "What I need is a vacation." When emphasizing an action, the pattern shifts to highlight the verb: "What he did was ruin the surprise."
This challenge will test your ability to construct these emphatic sentences flawlessly. You will explore standard wh-clefts, reversed wh-clefts (where the focus comes first, like "A vacation is what I need"), and action-focused clefts that require specific infinitive forms. You will also tackle tricky subject-verb agreement rules within these clauses and practice pseudo-cleft variations using "All" (e.g., "All I ever wanted was...").
Navigate through dramatic scenarios—from a detective's grand reveal to a roommate's culinary catastrophe—across 9 questions featuring multi-choice, single-choice, drop-down, and drag-and-drop formats.
Try the quiz to check your knowledge!
Choose the correct phrase to complete the detective's dramatic reveal.
The fingerprints were wiped clean, but what _____ that the security cameras had been disabled exactly two minutes before the heist.
The correct answer is really puzzled the investigators was.
In this wh-cleft sentence, the entire noun clause ("what really puzzled the investigators") acts as a singular subject. Therefore, it requires the singular verb "was".
Even though the word "investigators" is plural, it is the object of the verb "puzzled" inside the clause, not the subject of the main sentence. We use the past tense "was" to maintain agreement with the past narrative of the crime.
The correct answers are what, was, and order.
What introduces the pseudo-cleft clause ("what the panicked chef actually did"), which acts as the subject of the sentence.
Was is the singular linking verb. It is in the past tense to agree with the action ("did").
Order is a bare infinitive. In a Wh-cleft sentence that focuses on an action using a form of "do" (e.g., what he did), the emphasized action that follows the verb to be takes the form of a bare infinitive (or sometimes a full infinitive), rather than matching the tense of the main verb.
Help Juliet's best friend describe the tragic first date by dragging the correct words into the blanks.
Romeo thought he was being incredibly romantic. However, what he actually did was spill hot soup all over Juliet's brand-new dress. What she really wanted at that exact moment was a towel, not a dramatically recited poem!
Romeo thought he was being incredibly romantic. However, what he actually did was spill hot soup all over Juliet's brand-new dress. What she really wanted at that exact moment was a towel, not a dramatically recited poem!
did: In a wh-cleft sentence, the tense in the what-clause must logically align with the main verb. Since the main verb is the past tense "was," we need the past tense "did."
spill: This is a tricky advanced rule! When a wh-cleft focuses on an action (e.g., "What he did was..."), the focused verb takes the form of a bare infinitive (or sometimes a to-infinitive). Even though the sentence is in the past tense, using the past tense "spilled" here is grammatically incorrect.
wanted: Again, the past tense "wanted" is required to match the past tense "was" later in the sentence.
The correct answers are All I ever wanted was to retire to a quiet island. and What I have always wanted is to retire to a quiet island.
These are examples of pseudo-cleft sentences used for strong emphasis. You can use What or All (meaning "the only thing") to introduce the subject clause.
"All what" and "the thing what" are classic grammatical errors; what already means "the thing that," so combining them is redundant. Finally, the subject clause "What I want" is treated as singular, so it requires the singular verb is, not are.
Help the office manager finish his dramatic email to the lunch thief by dragging the correct words into the blanks.
You claim it was an innocent mistake. However, what you forgot to check was the security camera hidden above the microwave. A formal, written apology is what the HR department expects from you by 5 PM. Furthermore, all you actually achieved today was proving that you cannot be trusted with other people's yogurts!
You claim it was an innocent mistake. However, what you forgot to check was the security camera hidden above the microwave. A formal, written apology is what the HR department expects from you by 5 PM. Furthermore, all you actually achieved today was proving that you cannot be trusted with other people's yogurts!
forgot: The past tense "forgot" correctly agrees with the past tense verb "was" that links the two parts of the cleft sentence.
what: This is an inverted wh-cleft sentence. Instead of starting with "What," the focused element ("A formal, written apology") comes first, followed by the "be" verb ("is"), and finally the what-clause. "Which" and "how" do not form pseudo-cleft sentences in this manner.
all: We can use "all" (meaning "the only thing") instead of "what" to form a cleft sentence that adds a slightly different emphasis. "Whole" and "every" are incorrect because they require a following noun (e.g., "every thing").
The correct answers are what, What, and is.
what (first gap): This is a reversed Wh-cleft sentence (Focus + be + Wh-clause). "What" functions as a nominal relative pronoun meaning "the thing that." "That" and "which" cannot stand alone without a noun antecedent here.
What (second gap): This introduces a standard Wh-cleft sentence (Wh-clause + be + Focus) to place heavy emphasis on the source of his frustration.
is (third gap): The Wh-clause ("What frustrates me most") acts as a singular subject, so it takes the singular verb "is" to link it to the complement ("the terrible espresso machine").
The correct answers are What he did was set the kitchen on fire. and What he did was to set the kitchen on fire.
When a wh-cleft sentence focuses on an action (using the verb do in the wh-clause), the focused element after the verb be must be an infinitive clause. You can use either a bare infinitive ("set") or a to-infinitive ("to set").
Gerunds ("setting") are incorrect here. Additionally, the wh-clause ("What he did") must use normal statement word order, not question word order ("What did he do"), and the linking verb was cannot be omitted.
Select the grammatically correct phrase to complete the political journalist's article.
The public assumed the mayor resigned due to the recent embezzlement rumors. However, a sudden loss of support from her biggest donors _____ .
The correct answer is was what actually prompted her sudden exit.
This is an inverted wh-cleft sentence. In a standard wh-cleft, the wh- clause comes first (e.g., "What prompted her exit was a loss of support").
In the inverted version, the focused element ("a sudden loss of support") is moved to the front. It is then followed by the verb "to be" ("was") and finally the wh- clause ("what actually prompted her sudden exit"). Choosing "what actually prompted her sudden exit was" would incorrectly place the verb at the very end, leaving the sentence incomplete.
The correct answers are What the butler hid in the grandfather clock was the diamond. and The diamond is what the butler hid in the grandfather clock.
Wh-cleft sentences can be constructed in the standard order (What-clause + be + focused element) or reversed (Focused element + be + what-clause). Both options correctly isolate "the diamond" for dramatic emphasis.
The incorrect options contain structural errors: "What did the butler hide" incorrectly uses question word order inside a noun clause; "the thing what" is non-standard (it should be "the thing that"); and "were" is incorrect because the focused element "the diamond" is singular.
Clause
Clause vs phrase: a clause has a subject + verb (she runs); a phrase does not (in the morning, running fast). This is the first distinction to make when analysing sentence structure.
A clause is a grammatical unit built around a verb: independent clauses make complete sentences; dependent clauses attach to them as modifiers or complements.
Diagnostic: find the verb. If there's a subject doing or being something → clause. If there's no subject-verb pair → phrase.
Complex sentence
Complex vs compound sentence: a compound sentence links two equal independent clauses with and/but/or. A complex sentence links an independent clause with a subordinate (dependent) clause — one idea is the main point, the other is background.
A complex sentence = independent clause + dependent clause. The dependent clause adds time (when), reason (because), condition (if), or detail (who/which).
Diagnostic: are both halves able to stand alone? Yes → compound. Can only one stand alone? → complex.
Infinitive
Infinitive vs gerund: the #1 verb-pattern confusion. Some verbs take only infinitive (want to go ✅), some only gerund (enjoy going ✅), some both with different meanings (stop to smoke ≠ stop smoking). No logical rule exists — learn by verb.
The infinitive = base verb form used non-finitely. To-infinitive (to go) after certain verbs. Bare infinitive (go) after modals and causatives.
Diagnostic: what's the main verb? Check whether it takes to-infinitive, bare infinitive, or gerund. If unsure, try both and see which sounds natural to native speakers.
Inversion
Question inversion vs emphatic inversion: question inversion is basic grammar (Is she ready?) — every learner uses it. Emphatic inversion (Never have I seen…, Not only does she…) is a C1+ rhetorical tool for formal writing and speeches. Same mechanism, different register.
Inversion swaps subject + auxiliary order. Triggered by: questions, fronted negatives (Never, Rarely, Not only), and conditional if-deletion (Had I known…).
Diagnostic: is a negative/restrictive word at the front of a declarative sentence? → inversion required. Is it a question? → inversion is automatic.
Pronoun
Pronoun vs noun: nouns name explicitly (Sarah, the book). Pronouns substitute and point back (she, it). Pronouns are a closed class (you can't invent new ones easily), while nouns are open (new ones appear constantly). The main complication: pronouns still carry case marking that nouns have lost.
A pronoun replaces a noun or noun phrase. Types: personal, demonstrative, relative, interrogative, reflexive, indefinite.
Diagnostic: every pronoun must have a clear antecedent (the noun it replaces). If the reader can't tell which noun a pronoun refers to → ambiguity error.
Relative clause
Restrictive vs non-restrictive: this distinction changes meaning. The students who passed celebrated = only those who passed. The students*, who passed,** celebrated* = all students passed and all celebrated. One missing comma flips the meaning of the entire sentence.
A relative clause = dependent clause modifying a noun. Restrictive (essential, no commas) vs non-restrictive (extra, commas required).
Diagnostic: remove the clause. Does the sentence still identify the right noun? Yes → non-restrictive (add commas). No (now ambiguous) → restrictive (no commas).
Sentence
Sentence vs clause vs phrase: a phrase has no subject-verb pair. A clause has subject + verb. A sentence is one or more clauses packaged with end punctuation as a complete thought. These three levels — phrase ⊂ clause ⊂ sentence — are the structural hierarchy of English.
A sentence is the largest grammatical unit: one+ clauses ending with a period, question mark, or exclamation mark. Four structural types: simple, compound, complex, compound-complex.
Diagnostic: does it have at least one independent clause AND end punctuation? Yes → sentence. Missing independent clause? → fragment. Missing end punctuation? → run-on.
Subject
Subject vs object: the subject does or is; the object receives. She (subject) hit him (object). In English, position decides: subject comes before the verb, object after. Unlike inflected languages, English rarely marks subjects with case (exception: pronouns — I vs me).
The subject = who/what the sentence is about. Controls verb agreement. Usually a noun/pronoun before the verb.
Diagnostic: ask "who or what [verb]s?" The answer is the subject. The list of items is wrong — what is wrong? The list. That's your subject.
Verb
Verb vs noun vs adjective: nouns name things. Adjectives describe. Verbs express what happens or what IS. The test: can it take tense (walked, will walk)? Can it take -ing? Can it follow to as an infinitive (to walk)? Yes to any → verb. English often converts freely between classes (run = noun or verb), so context decides.
A verb = action/state/occurrence word. 5 forms (base, -s, past, past participle, -ing). Carries tense, aspect, mood, voice. The one required element in every sentence.
Diagnostic: does it change for tense (walk → walked)? Can you put to before it (to walk)? Does it take -ing (walking)? → verb.
Verb tense
Tense vs aspect: tense locates the action in TIME (past/present/future). Aspect describes its SHAPE — is it completed (perfect), ongoing (progressive), or just a fact (simple)? English combines these independently: was working = past (tense) + progressive (aspect). Confusing tense with aspect is why the 12-form grid feels overwhelming.
Verb tense = 3 time references × 3 aspects = 12 forms. Tense says when; aspect says how the action unfolds relative to that time.
Diagnostic: wrong time? → tense error. Right time but wrong "shape" (e.g., I work here for ten years instead of I've worked)? → aspect error.
Word order
English (SVO) vs other patterns: English relies on word ORDER to show who does what (Dog bites man ≠ Man bites dog). Inflected languages (Latin, Russian, German) use case endings and can scramble order freely. In English, changing order changes meaning or requires special constructions (inversion, cleft sentences).
Word order = how English marks grammatical relationships. SVO is the default; fixed adjective order; adverb placement varies by type.
Diagnostic: does your sentence sound "off" even though all word forms are correct? → probably a word order issue. Try moving the element back to default SVO position.
C1 | Advanced
C1 vs C2: C1 means fluent and flexible use with occasional gaps in very unfamiliar domains. C2 means native-like command of idiom, irony, and register across any subject. If you can handle advanced grammar but still miss cultural nuance or very rare idioms, you're C1.
C1 is the advanced CEFR level: inversion, cleft sentences, subjunctive mood, advanced conditionals, and precise register control in professional and academic contexts.
Diagnostic: can you write persuasively in different registers and catch subtle irony? Consistently → C2. Sometimes → C1.
Hard
Hard vs Medium: Medium tests one rule with realistic distractors. Hard tests interacting rules, edge cases, or context-dependent answers where multiple options seem correct until you think deeply. If you're scoring 80%+ on Medium, try Hard to find your real gaps.
The Hard tag filters for B2+ challenges with layered difficulty: rule interactions, subtle distractors, and contexts that demand genuine grammatical reasoning.
Diagnostic: if Hard questions feel impossible, drop to Medium and master the individual rules first. Hard assumes you already know each rule — it tests whether you can apply them together.