Tenses & Conditionals - Deep Mastery

Tense = Time + Aspect. Time: Past, Present, Future. Aspect: Simple (habit/fact), Continuous (ongoing), Perfect (completed), Perfect Continuous (duration).

3x4=12 tenses. Example with verb 'eat':
Present: I eat (simple), I am eating (continuous), I have eaten (perfect), I have been eating (perfect continuous)
Past: I ate, I was eating, I had eaten, I had been eating
Future: I will eat, I will be eating, I will have eaten, I will have been eating

Why deep? Exams don't ask structure only, they trap you with time markers: since/for, yet/already, when clause no future, stative verbs no continuous.

Stative vs Dynamic: Dynamic verbs show action can be continuous: eat, go, run, write. Stative show state, feeling, ownership, thought - generally NO continuous: know, believe, understand, like, love, hate, want, need, belong, own, possess, seem, appear. But some stative can be dynamic with different meaning: I'm thinking about you (considering) vs I think you are right (opinion).

1. Present Simple: Subject + V1 / V1+s/es
Uses: Habit (I go daily), Fact (Sun rises in east), Timetable (Train leaves at 6), Story/narration, Conditional clause (If it rains...).
Time markers: always, usually, often, sometimes, never, every day/week.
Trap: With he/she/it add s/es: He goes, She watches. But with does: Does he go? (not goes).
Stative in simple: I know him (not am knowing).

2. Present Continuous: is/am/are + V-ing
Uses: Now (I am eating now), Temporary (I am living in Delhi these days), Annoying habit (He is always complaining), Future plan (I am meeting him tomorrow).
Markers: now, at the moment, these days, currently, always for annoyance.
No stative: I am knowing ❌ => I know.

3. Present Perfect: has/have + V3
Uses: Past action with present result (I have finished - result: free now), Experience (I have been to Goa), Just completed (I have just arrived), Since/for duration till now (I have lived here for 5 years / since 2020).
Markers: already, yet (negative/question), just, ever, never, so far, up to now, since/for.
Rule: Yet always at end in negative/question: Have you finished yet? Not yet.
Difference Simple Past vs Present Perfect: Simple past finished time (yesterday, last week, in 2020). Present perfect no finished time: I ate yesterday (simple past) vs I have eaten (no time, present relevance).

4. Present Perfect Continuous: has/have been + V-ing
Uses: Started in past, continues till now, maybe further: I have been waiting for 2 hours (still waiting). Emphasis on duration.
Markers: for + duration (for 2 hours), since + point (since morning), all day/morning, how long.
Since vs For: Since = point (since Monday, since 8am, since 2010). For = period (for 2 hours, for 5 years, for ages). Trick: Since = WHEN started, For = HOW LONG.

1. Past Simple: Subject + V2
Uses: Finished past, no connection to now: I visited Delhi last year. Habit in past (often with used to): I used to play cricket. Story narration.
Markers: yesterday, last week/month/year, ago, in 2020, in the past.
Used to vs Would: Used to for past habit/state (I used to be fat), Would for repeated past action not state (When I was child, I would play daily). Would not for state.

2. Past Continuous: was/were + V-ing
Uses: Ongoing in past at specific time (I was sleeping at 10pm), Interrupted action: I was eating when he came (was eating = longer, came = shorter simple past). Two simultaneous past: While I was cooking, she was reading.
Markers: at that time, at 8pm yesterday, when, while.

3. Past Perfect: had + V3
Uses: Earlier of two past actions: The train had left before I reached. Order: First action past perfect, second simple past. Also for unreal past wish: I wish I had studied harder.
Rule: Never use had with before alone in simple sentences, use after before? Actually Past perfect used with before/after to show earlier action: He had left before I came.
Markers: before, after, already, by the time.

4. Past Perfect Continuous: had been + V-ing
Uses: Duration before a past point: I had been waiting for 2 hours when he came. Expected action but didn't happen: He had been trying to call but couldn't.
Past Perfect vs Simple Past Trap: When two past actions with when/before/after, earlier = past perfect, later = simple past. I had finished homework when he called (finish first, call second).

1. Future Simple: will/shall + V1
Will for all persons in modern English, shall for I/we for formal/offer/suggestion: Shall I help you? Shall we go?
Uses: Prediction (It will rain), Decision now (I will call him), Promise, Offer, Threat.
Going to vs Will: Going to for prior plan/intention/evidence: I am going to buy a car (already planned), Look at clouds, it is going to rain (evidence). Will for instant decision/no prior plan: Phone ringing - I will pick up.
Shall rule: In interrogative I/we: Shall I/we... for suggestion/offer. In assertive, shall only for legal/formal.

2. Future Continuous: will be + V-ing
Uses: Ongoing at future time: I will be traveling at this time tomorrow. Polite enquiry: Will you be coming to party?
Markers: at this time tomorrow, at 8pm tomorrow.

3. Future Perfect: will have + V3
Uses: Completed before future point: By next year, I will have finished degree. By 5pm, he will have left.
Markers: by + future time, by then, before.

4. Future Perfect Continuous: will have been + V-ing
Uses: Duration till future point: By next month, I will have been working here for 5 years.
Future in Past: When reporting future from past: He said he would come (will -> would).

Conditional = If clause + Main clause. If shows condition.

Zero Conditional (Fact/Truth): If + Present, Present
General truth, scientific fact, habit: If you heat ice, it melts. If it rains, roads get wet. Both clauses present simple. Can use when instead of if for fact.

First Conditional (Real Possible Future): If + Present, will + V1
Real possibility in future: If it rains, I will stay home. If you study, you will pass. Structure: If + V1/V1+s, will/can/may + V1. Can also use imperative: If you are hungry, eat something.
Variations: If + present, present (for instruction), If + present, may/might (possibility).

Second Conditional (Imaginary Present/Future - Unlikely): If + Past, would + V1
Imaginary, unlikely, advice: If I won lottery, I would travel. If I were you, I would study (were used for all persons in imaginary, not was - subjunctive). Structure: If + V2/were, would/could/might + V1.
Important: If I were you (not was) - subjunctive mood for imaginary. If he were rich...
Use for advice: If I were you, I would...

Third Conditional (Imaginary Past - No Change Possible): If + had + V3, would have + V3
Past imaginary, regret, no chance to change: If she had studied, she would have passed. If you had called, I would have come.
Structure: If + had + V3, would/could/might have + V3.

Mixed Conditional (Past Condition, Present Result): If + had + V3, would + V1
Past action affects present: If I had studied medicine, I would be a doctor now (past condition had studied, present result be doctor). If he had listened, he would be safe now.
Reverse Mixed: If + V2, would have + V3 (present condition, past result): If I were smarter, I would have taken that job.

Unless, Provided, As long as, In case:
- Unless = if not: Unless you work hard, you will fail (= If you don't work hard). Never use not with unless: Unless you don't work ❌
- Provided/providing that, as long as, supposing = if
- In case = as precaution: Take umbrella in case it rains.

Inversion (Formal, No If):
Had I known, I would have come (= If I had known). Were I you, I would go (= If I were you). Should you need help, call me (= If you should need).

Sequence of Tenses: When main clause past, subordinate usually past. He said he was busy (not is). He said he had finished (not has finished). But if subordinate is universal truth, present allowed: He said Sun rises in east (truth remains present).

Time Clauses - GOLDEN RULE: No Future in Time Clause (When, While, Before, After, As soon as, Till, Until, By the time)
Even if future meaning, time clause uses PRESENT, main clause future.
When he comes (not will come), I will call you. Correct: When he comes, I will call you.
Until he comes, I will wait.
As soon as it stops raining, we will go out.
Before you leave, call me.
After he finishes, he will go.
Why? Time clause is condition/time, not main prediction. So present tense gives future meaning in time clause.
Exception: When time clause is question or not future reference, future allowed, but in conditional future exam rule: no will/shall in time clause for future meaning.

Other conjunctions with same rule: If, unless, in case, provided, as long as, the moment, the instant, immediately - all take present for future meaning: If it rains, I will stay. Unless you study, you will fail.

By the time: By the time he comes, I will have finished (present in by the time clause, future perfect in main).

Since vs For: Since = point (since Monday, since 8am, since 2010, since childhood). For = period (for 2 hours, for 5 years, for ages, for a long time).
Use with perfect tenses: I have lived here for 5 years / since 2020.
Common Error: I have lived here since 5 years ❌ => for 5 years. I have lived here for Monday ❌ => since Monday.

Yet vs Already:
Yet = expected to happen, negative/question, at END: Have you finished yet? I haven't finished yet.
Already = happened before now, statement/question, mid position: I have already finished. Have you already eaten?
Trap: I have finished yet ❌ => already. Have you already finished yet? ❌ => Have you finished yet? OR Have you already finished?

Still vs Just:
Still = continues up to now: I'm still studying, He is still here.
Just = very recently: I've just arrived (a moment ago).
Error: I have just been here for 2 hours ❌ => I have been here for 2 hours. Just = moment ago, not duration.

Ever vs Never:
Ever = at any time in life, question: Have you ever been to Japan?
Never = at no time, negative: I have never been to Japan.
Error: I've ever been there ❌ => never. Have you never been there ever? ❌ => Have you ever been there?

Other tricky:
- Still, yet, already position: Still before verb (still studying), yet at end, already mid (already finished).
- How long, For how long, Since when for questions.
- All day/morning with perfect continuous: I have been reading all day.

All 12 Tenses Quick Structures:
Present: I eat (V1), I am eating (is+V-ing), I have eaten (has+V3), I have been eating (has been+V-ing)
Past: I ate (V2), I was eating (was+V-ing), I had eaten (had+V3), I had been eating (had been+V-ing)
Future: I will eat (will+V1), I will be eating (will be+V-ing), I will have eaten (will have+V3), I will have been eating (will have been+V-ing)

Conditionals:
Zero: If+Present, Present (fact): If you heat ice, it melts.
First: If+Present, will+V1 (real future): If it rains, I will stay.
Second: If+Past, would+V1 (imaginary present, were for all): If I were you, I would go.
Third: If+had+V3, would have+V3 (imaginary past): If she had studied, she would have passed.
Mixed: If+had+V3, would+V1 (past->present): If I had studied medicine, I would be a doctor now.

Golden Rules:
- Time clause no future: When he comes, I will call.
- Since point, For period, Yet end, Already mid.
- Stative no continuous: I know, not am knowing.
- Unless = if not, no not with unless.
- Inversion: Had I known, Were I you, Should you need.