Help the HR manager complete her slightly concerning hiring report by choosing the correct phrase.
The committee interviewed fifteen candidates for the dragon-tamer position, _____ had any actual experience with fire-breathing reptiles.
The correct answer is none of whom.
Because the two clauses are joined only by a comma, we must use a relative pronoun to create a non-defining relative clause. "None of them" would create a comma splice (two independent clauses improperly joined by a comma).
Furthermore, because the pronoun follows the preposition "of" and refers to people (candidates), we must use the objective case "whom" rather than "who" or "which."
Relative clause
- ✅ The man who called is my uncle. — restrictive (essential: which man?)
- ✅ My uncle, who lives in Paris, called. — non-restrictive (extra info, commas)
- ❌ My uncle that lives in Paris — wrong (that can't introduce non-restrictive)
- ✅ The book that I read = The book I read — restrictive (pronoun optional)
Relative clauses modify nouns using who/whom/whose/which/that or where/when/why. Restrictive = essential, no commas, that OK. Non-restrictive = extra, needs commas, uses which/who (never that).
Rule: if you can remove the clause and still know which noun is meant → non-restrictive (commas). If removing it makes the noun ambiguous → restrictive (no commas).
Pronoun
- ✅ between you and me — ❌ between you and I (objective case after preposition)
- ✅ its colour — ❌ it's colour (it's = it is)
- ✅ She did it herself. — reflexive pronoun
- ✅ The person who called… — relative pronoun
Pronouns replace nouns: personal (I/me/my), demonstrative (this/that), relative (who/which/that), interrogative (who?/what?), reflexive (myself), indefinite (everyone/nobody). They carry case that nouns have lost.
Trap: pronouns are where English case still matters: I vs me, who vs whom, its vs it's. Get these wrong and it's instantly noticeable.
Preposition
- ✅ interested in — ❌ interested on
- ✅ good at football — ❌ good in football
- ✅ depend on — ❌ depend of
- ✅ arrive at the station — ❌ arrive to the station
Prepositions link nouns to the rest of the sentence: time (at 5pm), place (in London), manner (with care), abstract (afraid of). Most are idiomatic — the "correct" preposition must be memorised with each verb/adjective combination.
Rule: there is no universal rule. English prepositions are learned by combination: interested IN, good AT, depend ON, afraid OF. Your native language's equivalent will often mislead.
Comma
- ✅ apples, pears, and figs — list separator
- ✅ My brother, a doctor, called. — non-essential info set off by commas
- ✅ I went home, and she stayed. — comma before conjunction joining two clauses
- ❌ I went home and she stayed. — missing comma (two independent clauses need one before and)
The comma ( , ) separates elements within a sentence: list items, non-essential phrases, introductory words, and clauses joined by coordinating conjunctions.
Rule: if two independent clauses are joined by and/but/or, put a comma before the conjunction. If it's just a compound verb (same subject), no comma.
Complex sentence
- ✅ Because I overslept, I missed the bus. — dependent clause (reason) + independent
- ✅ The man who called is my uncle. — relative clause inside the sentence
- ✅ If it rains, we'll stay inside. — conditional dependent + independent
- ❌ Because I overslept. — fragment (dependent clause alone)
A complex sentence pairs an independent clause with one or more dependent clauses linked by subordinating conjunctions (because, although, if, when) or relative pronouns (who, which, that).
Pattern: independent clause = the main point. Dependent clause = the background, reason, or condition. Move the dependent clause around for emphasis.
C1 | Advanced
- ✅ Not only did she finish early, but she also helped others. — inversion for emphasis
- ✅ It is the process that matters, not the result. — cleft sentence
- ✅ I insist that he be present. — formal subjunctive
- ✅ Were I to disagree, I would say so. — inverted conditional
These are C1 structures — the CEFR advanced level. At C1 you control inversion, cleft sentences, subjunctive forms, and register-switching fluently across formal and informal contexts.
Marker: if you can restructure a sentence for rhetorical effect without hesitation, you're C1.
Hard
- Had she not intervened, the situation would have escalated. — inverted conditional
- All distractors are grammatically plausible in other contexts
- Multiple rules interact (e.g., tense + aspect + modality)
- Context determines the answer — no single "rule" is enough
Hard marks upper-intermediate to advanced challenges: B2+, interacting rules, edge cases, plausible distractors, and contexts where pattern-matching fails.
Use "Hard" when Easy/Medium feel trivial and you want to test whether you actually understand a rule versus just recognising surface patterns.