Fronted Prepositions in Relative Clauses
In highly formal English, sentences generally do not end with a preposition. Instead, the preposition is moved to the front of the relative clause, placed directly before the relative pronoun. For example, instead of writing "the person who I spoke to," a strict formal register requires "the person to whom I spoke." Similarly, "the project that we worked on" becomes "the project on which we worked."
This challenge will test your ability to construct these advanced grammatical structures across a variety of dramatic and professional scenarios. You will help a snooty food critic use phrases like "with which," draft a strict etiquette manual with a head butler, and assist an anxious job applicant with "to whom." You'll also navigate complex structures like "on whose approval," "extent to which," and "from which" while completing a spaceship captain's bizarre daily log and an 18th-century historian's academic paper.
You'll work through 12 questions in a mix of single-choice, multi-choice, drop-down, and drag-and-drop formats. Try the quiz to check your knowledge!
The correct answers are The monarch to whom the secret letter was addressed never received it. and The controversial treaty upon which the two nations agreed was signed in 1812.
In highly formal English, prepositions are often placed before the relative pronoun rather than at the end of the clause.
When placing a preposition before a relative pronoun, you must use whom (for people) or which (for things). You cannot use who or that immediately after a preposition.
While "The monarch whom the secret letter was addressed to..." is grammatically valid in everyday English, it leaves the preposition stranded at the end, which does not fit the strict formal requirement of "fronting" the preposition asked for in the prompt.
Help the detective complete her dramatic final report by choosing the grammatically correct option.
The mysterious informant _____ the detective confided turned out to be the mastermind all along!
The correct answer is in whom.
In formal English, prepositions (like "in") are placed before the relative pronoun. When referring to a person immediately following a preposition, you must use the objective case whom. You cannot use "who" or "that" right after a preposition in a relative clause!
Complete the spaceship captain's bizarre daily log by dragging the correct formal prepositional phrases into the text.
The highly advanced alien species with which we just made contact unexpectedly offered us a platter of space-tacos. Meanwhile, the mysterious glowing orb for which we are now responsible has started humming an upbeat pop tune. I am beginning to suspect that the uncharted galaxy from which our ship just emerged is actually a giant cosmic amusement park.
The highly advanced alien species with which we just made contact unexpectedly offered us a platter of space-tacos.
The phrase is "make contact with someone/something." In a formal relative clause, the preposition "with" shifts to the front of "which."
Meanwhile, the mysterious glowing orb for which we are now responsible has started humming an upbeat pop tune.
The adjective "responsible" is followed by the preposition "for" (responsible for the orb).
I am beginning to suspect that the uncharted galaxy from which our ship just emerged is actually a giant cosmic amusement park.
The verb "emerge" pairs with the preposition "from" (emerge from the galaxy).
The correct answers are The crystal glasses in which the vintage wine is served must be polished twice. and The dignitaries to whom you will serve afternoon tea are seated in the parlor.
Just like Mr. Belvedere's uniform, formal grammar has strict rules! When a preposition is moved to the front of a relative clause, it can only be followed by which (for objects like glasses) or whom (for people like dignitaries).
"In that" and "to who" are grammatically incorrect.
The sentence ending in "...resides in" is grammatically acceptable in standard English, but it strands the preposition at the end, failing Mr. Belvedere's strict formal requirement.
Complete the snooty food critic's latest scathing review by selecting the correct formal phrase.
The alarming enthusiasm _____ the waiter presented the deep-fried grasshoppers completely ruined my appetite.
The correct answer is with which.
We do things "with enthusiasm," so the relative clause needs the preposition "with." In a formal register, the preposition is moved to the front of the relative clause, right before which. Remember, the relative pronoun "that" can never immediately follow a preposition!
The correct answers are from which and with whom.
In official or formal registers, we avoid ending a sentence with a preposition (preposition stranding) by moving the preposition before the relative pronoun.
- A transmission originates from a place, giving us "from which." ("That" cannot follow a preposition).
- You negotiate with someone. When referring to a person after a preposition, you must use the objective case "whom," giving us "with whom."
Help the detective complete her formal report on the great penguin heist by dragging the correct prepositional phrases to their matching clauses.
The exact extent to which the zookeeper was involved remains a heavily guarded secret. Furthermore, the absurd premise on which the entire heist was based makes absolutely no logical sense. Finally, the highly suspicious manner in which the penguin vanished suggests a mastermind at work.
The exact extent to which the zookeeper was involved remains a heavily guarded secret.
We use "to which" because the standard phrase is "the extent to something."
Furthermore, the absurd premise on which the entire heist was based makes absolutely no logical sense.
We use "on which" because we "base something on a premise."
Finally, the highly suspicious manner in which the penguin vanished suggests a mastermind at work.
We use "in which" because things happen "in a certain manner."
The correct answers are We discovered fifty critical bugs, most of which were caused by the recent update. and I spoke directly to the senior engineers, several of whom denied any responsibility.
When combining quantifiers (like most, several, all, none) with a preposition (usually of) in a relative clause, you must use which for things and whom for people.
"Most of that" and "several of who" are incorrect.
Additionally, "most of which they were caused" is incorrect because "which" already acts as the subject of the relative clause; adding "they" creates a double subject!
The correct answers are to whom and under which.
In highly formal English, prepositions are placed before the relative pronoun rather than at the end of the clause.
- We say "addressed a letter to someone," so the formal relative structure is "to whom." ("Who" cannot be used immediately after a preposition).
- We say "operate under conditions," so the formal relative structure is "under which." ("That" can never be used immediately after a preposition in a relative clause).
Help the eccentric professor complete his rather alarming report to the safety committee.
The highly explosive chemical compound _____ yesterday has mysteriously vanished from the laboratory.
The correct answer is with which I was experimenting.
The verb phrase is "experiment with." In formal writing, we shift the preposition to the beginning of the relative clause ("with which").
Watch out for the sneaky double preposition trap! If you move "with" to the front, you cannot leave another "with" at the end of the clause.
The correct answers are upon which and to which.
When a preposition is moved to the front of a relative clause, it must match the verb or noun it belongs to.
- A foundation is built upon (or on), so we use "upon which." We cannot use "that" directly after a preposition.
- The noun "extent" strongly collocates with the preposition "to" (e.g., "to a great extent"). Therefore, the correct formal relative phrase is "the extent to which."
Complete the stressed college student's complaint about their thesis by dragging the correct formal relative clauses into the blanks.
The esteemed professor on whose approval my entire academic future depends just sighed heavily at my first draft. Worse still, the obscure historical texts to which I am referring throughout the essay were mostly found on a dubious fan forum. To top it all off, the study group members with whom I collaborated spent the whole time watching cat videos!
The esteemed professor on whose approval my entire academic future depends just sighed heavily at my first draft.
We say "depend on someone's approval." Because the approval belongs to the professor, we use the possessive relative pronoun "whose" combined with the preposition "on."
Worse still, the obscure historical texts to which I am referring throughout the essay were mostly found on a dubious fan forum.
The verb "refer" takes the preposition "to" (refer to texts). In formal English, the preposition moves before the relative pronoun "which."
To top it all off, the study group members with whom I collaborated spent the whole time watching cat videos!
You "collaborate with someone." Since the members are people, we use the object pronoun "whom" after the preposition "with."
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.
Phrase
Phrase vs clause: a phrase has NO subject-verb pair (on the table, the old man). A clause HAS a subject-verb pair (the man sat, because she left). This is the fundamental structural division in grammar — clauses contain phrases, not the other way around.
A phrase = group of words functioning as one unit: noun phrase, verb phrase, prepositional phrase, adjective/adverb phrase. No subject + verb.
Diagnostic: does the word group have both a subject AND a verb? Yes → clause. No → phrase. Name the head word to identify the phrase type (noun = NP, preposition = PP, etc.).
Possessive
Noun possessive vs pronoun possessive: nouns ADD an apostrophe for possession (Sarah's, students'). Pronouns NEVER use apostrophes (its, yours, theirs — no apostrophe). This contradiction is why its/it's is the most common error in English writing.
The possessive marks ownership: 's for singular nouns, s' for plural nouns ending in s, and special pronoun forms (my/mine, their/theirs).
Diagnostic: is it a noun? → add 's or s'. Is it a pronoun? → use the built-in possessive form (NO apostrophe). Specifically its (possessive) vs it's (it is).
Preposition
Preposition vs particle: same words (in, on, up, off), different jobs. A preposition links to a noun (look at the book). A particle changes verb meaning without a noun (give up = quit). Test: is there a noun/pronoun after it forming a prepositional phrase? → preposition. Does it change the verb's meaning? → particle in a phrasal verb.
A preposition = small word connecting a noun to the sentence (time, place, manner, relationship). Choice is idiomatic per verb/adjective combination.
Diagnostic: struggling with which preposition to use? It's almost never about logic — look up the specific verb/adjective + preposition combination.
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).
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.
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.
Collocations
Collocation vs idiom: both are fixed expressions, but collocations are transparent (you can guess the meaning from the words: heavy rain = a lot of rain), while idioms are opaque (kick the bucket ≠ literally kick anything). Collocations are about which words pair naturally; idioms are about hidden meaning.
Collocations are habitual word combinations: make a decision, strong coffee, take a shower. Grammar allows alternatives, but fluency demands the conventional pairing.
Diagnostic: if the meaning is clear but the combination sounds "off" to native ears (do a mistake instead of make a mistake) — it's a collocation issue.
B2 | Upper Intermediate
B2 vs C1: B2 means effective communication on complex topics with some effort. C1 means effortless fluency with precise register control. If you can argue a point but still reach for words and make structural slips under pressure, you're B2.
B2 is the upper-intermediate CEFR level: mixed conditionals, complex passives, reported speech with backshift, participle clauses, and sustained written argument.
Diagnostic: does your writing read as "competent non-native" or "could be native"? The former → B2. The latter → 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.