Grammar
What you'll learn
- Form and use all four types of conditional sentences correctly
- Use the subjunctive mood in formal and hypothetical contexts
- Apply inversion for emphasis in formal writing
- Distinguish between defining and non-defining relative clauses
Key concepts
The Four Conditional Structures
| Type | Condition | Result | Use |
|---|---|---|---|
| Zero | If + present simple | present simple | Universal truths and facts |
| First | If + present simple | will + V1 | Real, likely future situation |
| Second | If + past simple | would + V1 | Unreal/hypothetical present or future |
| Third | If + past perfect | would have + V3 | Unreal/impossible past situation |
Zero Conditional — General Truth
"If you heat water to 100°C, it boils." "If it rains, the ground gets wet."
No time restriction — this is always true.
First Conditional — Real Possibility
"If she studies hard, she will pass the exam." "If you leave now, you will catch the train."
The "if-clause" uses present simple even though it refers to the future. Never use "will" in the if-clause.
Second Conditional — Unreal Present/Future
"If I were rich, I would travel the world." "If she knew the answer, she would tell us."
Note: Use "were" for ALL persons with "be" in second conditional (not "was"), especially in formal writing.
Third Conditional — Unreal Past (Regret/Criticism)
"If he had studied, he would have passed." "If they had left earlier, they would not have missed the flight."
Mixed conditional (past → present result): "If she had taken the medicine then, she would be fine now." (Past condition + present result — mix 3rd and 2nd)
Common Conditional Mistakes
| Mistake | Correct form |
|---|---|
| If I will go… | If I go… |
| If he was… (subjunctive) | If he were… |
| If she would have told me… | If she had told me… |
| I would have went | I would have gone (use V3) |
The Subjunctive Mood
The subjunctive expresses wishes, hypothetical situations, demands, suggestions, and formal recommendations. The verb takes its base form regardless of the subject.
Structures that trigger subjunctive:
- It is essential / important / vital / necessary + that + Subject + V1 (base form)
- Verbs: suggest, recommend, insist, demand, propose, request + that + Subject + V1
Examples: "It is essential that every student submit the form by Friday." (NOT submits) "The doctor recommended that she rest for a week." (NOT rests) "I insist that he be present at the meeting." (NOT is)
Formal writing: The subjunctive is common in academic and professional English. In informal speech, people often use "should": "It is essential that everyone should submit…" — both are acceptable.
Inversion for Emphasis
Inversion places the auxiliary verb before the subject to create emphasis or formality. Common in formal writing and literary texts.
| Trigger phrase | Normal order | Inverted (emphatic) |
|---|---|---|
| Never | I have never seen this. | Never have I seen this. |
| Seldom / Rarely | She rarely makes mistakes. | Seldom does she make mistakes. |
| Not only…but also | He not only sings but also dances. | Not only does he sing but he also dances. |
| Hardly / Scarcely | She had hardly sat down when… | Hardly had she sat down when… |
| Only then | They only then realised… | Only then did they realise… |
| No sooner…than | He had no sooner arrived than… | No sooner had he arrived than… |
Inversion requires a change to question word order: auxiliary before subject. The main verb stays in its normal position.
Relative Clauses — Defining vs Non-Defining
Defining relative clause: Identifies which specific person/thing is meant. No commas. Cannot be removed without changing meaning. "The student who scored 100% received a scholarship." (Tells us WHICH student — essential information)
Non-defining relative clause: Adds extra information. Commas required. Can be removed without affecting the core meaning. "Priya, who scored 100%, received a scholarship." (Priya is already identified by name — the clause adds bonus info)
| Feature | Defining | Non-defining |
|---|---|---|
| Commas | No | Yes |
| "that" allowed? | Yes | No |
| Can be removed? | No | Yes |
| Refers to? | Specific (unknown) item | Already-identified item |
Quick check
- Fill in: "If the temperature _____ (drop) below 0°C, water _____ (freeze)." (Which conditional?)
- Correct the error: "If she would arrive on time, we would start."
- Write the subjunctive form: "It is vital that he _____ (attend) the meeting."
- Rewrite with inversion: "She has never made such a mistake before."
- Add or remove commas as needed: "The book that I lent you is a first edition." and "Moby Dick which was written by Melville is a classic."
Open the Practice tab for graded questions on Advanced Grammar.
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