Conditionals

Why A is correct:
In conditional sentences (if + condition, result), use the present tense in the "if" clause, even though you're talking about a future situation. "If it rains" follows this rule.

Why the others are wrong:
- B (rain): Missing the third-person singular "-s" needed with "it"
- C (rained): Past tense doesn't fit; you're describing a possible future event, not something that already happened
- D (will rain): Never use "will" in the if-clause of a conditional sentence; "will" goes in the main clause ("I will not go")

Correct answer: A. had studied

This is a third conditional sentence (also called mixed conditional), which describes an imaginary past situation and its result. The structure is: "If + had + past participle, would have + past participle." The sentence means she didn't study, so she didn't pass.

Why the others are wrong:
- B. study – Present tense doesn't work for past situations
- C. studied – This is second conditional (simple past), which describes imaginary present situations, not past ones
- D. will study – Future tense contradicts the past context of "would have passed"

Correct answer: A (were)

This sentence uses a contrary-to-fact conditional (an "if I were you" structure). When expressing an imaginary or hypothetical situation that contradicts reality, English uses "were" with all subjects, even singular ones like "I." The structure is: "If I were [in your situation], I would [do this]."

Why the others are wrong:
- B (am): Present tense doesn't work here; we need the subjunctive form for hypotheticals
- C (was): This is standard past tense, but the subjunctive "were" is required for contrary-to-fact conditions
- D (have been): This is present perfect tense, which doesn't fit this hypothetical structure

Why A is correct:
This sentence needs the past perfect tense ("had known") because it describes a hypothetical situation in the past—something that didn't actually happen. The structure "If I had known... I would have taken" is the classic third conditional, used for imagining different outcomes to past events.

Why the others are wrong:
- B (know): Present tense doesn't fit; this isn't about now.
- C (knew): Simple past suggests a real situation ("If I knew... I would..."), but we need past perfect for an unreal past scenario.
- D (have known): Present perfect doesn't work here; we need past perfect for the "if" clause in third conditionals.

Why A is correct:
This is a past conditional (if + past perfect). The sentence structure "if they ____ enough money, they would have bought" requires "had" to show a hypothetical situation that didn't happen in the past.

Why the others are wrong:
- B (have): Present tense doesn't fit the past conditional structure or the "would have bought" consequence
- C (has): Third-person singular doesn't match "they" (plural subject)
- D (will have): Future tense contradicts the past conditional meaning and "would have bought"

Correct answer: A. had studied

This is a second conditional (past unreal) sentence showing a hypothetical situation that didn't happen. The structure "if + past perfect, would have + past participle" expresses "if this had happened in the past, then this different past outcome would have occurred." "Had studied" fits because it shows he didn't study, and that's why he failed.

Why the others are wrong:
- B. studied – Simple past doesn't work here; it describes what actually happened, not an unreal hypothetical
- C. studies – Present tense doesn't fit a sentence about past events
- D. will study – Future tense contradicts the "wouldn't have failed" (past) part of the sentence

# Explanation

A. had known ✓ Correct
- This is the third conditional (past unreal situation). It expresses something that didn't happen in the past and its imaginary consequence: "If I had known (but I didn't), I would have called (but I didn't)."

B. know
- Present tense doesn't fit. The sentence already contains "would have called" (past), so we need a past conditional, not present.

C. knew
- This is second conditional (present/future unreal), which would mean "If I knew now, I would call now"—but the main clause says "would have called" (already happened), creating a mismatch in time.

D. will know
- Future tense doesn't work here. The whole sentence refers to a past situation that already occurred, not something that might happen later.

Correct Answer: A (were more positive)

This uses the past tense "were" in a conditional sentence (if + past tense = hypothetical situation). The sentence describes an imaginary situation that isn't currently true, so we need the past tense form to show it's not real.

Why others are wrong:

• B (are more positive) — Present tense doesn't work in conditional "if" clauses about hypothetical situations
• C (were positive) — While grammatically possible, it's less natural; "more positive" (comparative) fits better with "happier" (comparative)
• D (will be more positive) — Future tense doesn't belong in this type of conditional; it breaks the if + past tense pattern for hypothetical situations

A. are ✓
This is correct because "you" is a second-person pronoun that always pairs with "are" (you are, you were). This is the conditional statement structure: "If you [are happy], clap your hands."

B. am ✗
"Am" only goes with "I," not "you."

C. is ✗
"Is" goes with third-person singular subjects like "he," "she," or "it," not "you."

D. be ✗
While "be" is the base verb form, it doesn't work here—you need the conjugated form "are" to match the subject "you."

Correct answer: A (had paid)

This sentence describes a hypothetical past situation—you didn't pay attention *then*, and now you don't understand. The structure "If you had paid... you would understand" is a mixed conditional, combining a past condition with a present result. "Had paid" (past perfect) is correct.

Why the others are wrong:
- B (pay): Simple present tense doesn't work here; it suggests a general habit, not a hypothetical past situation.
- C (paid): Simple past tense alone doesn't convey the hypothetical meaning needed; it would sound like a statement of fact rather than an unreal condition.
- D (paying): Gerund form doesn't fit the grammatical structure of conditional sentences.

A. cools ✓

This sentence needs a present-tense verb to show a general fact or condition. "If water cools to 0°C, it freezes" describes what *always happens*—a rule of nature.

B. cool – Missing the third-person singular ending; "water" is singular and needs "-s"

C. cooled – Past tense doesn't fit; this isn't about something that already happened

D. will cool – Future tense breaks the pattern; conditional "if" statements use present tense for both the condition and result

Why A is correct:
This sentence uses a past conditional (also called the third conditional). The structure is "If + had + past participle, would have + past participle." It describes an imaginary past situation that didn't actually happen. "If I had married Paul" fits this pattern perfectly.

Why the others are wrong:
- B (have): This would be present perfect, but the main clause says "would have lived" (past), so tenses don't match.
- C (has): This is third-person singular present tense, which doesn't fit the conditional structure at all.
- D (having): This is a gerund/present participle, not the correct form for conditional sentences.

Correct Answer: A. had worked

This sentence describes a past situation that didn't happen, so it needs the past perfect tense ("had worked"). It expresses a hypothetical regret—you didn't work hard, so you don't have a better job now.

Why the others are wrong:

• B. worked — Simple past tense describes something that actually happened, not a hypothetical situation.
• C. have worked — Present perfect doesn't fit the past condition; it suggests an ongoing action up to now.
• D. was working — Past continuous describes an action in progress at a specific time, not a hypothetical condition.

Why A is correct:
"Were" is the correct subjunctive form used for wishes about hypothetical or contrary-to-fact situations. Since you're not actually taller, you use the subjunctive mood: "I wish I *were* taller."

Why the others are wrong:
- B (was): Indicative past tense; used for real events, not wishes or hypotheticals
- C (is): Present tense; doesn't fit the structure "I wish I..." which requires subjunctive
- D (be): This is the base form; while sometimes used in formal subjunctive, "were" is the standard subjunctive form for "I wish" statements

A. had done ✓

This sentence expresses a regret about the past—wishing you had done something at an earlier time. You need the past perfect tense ("had done") to show that one past action happened before another past moment.

Why the others are wrong:
- B. done – Incomplete; missing the auxiliary verb "had"
- C. did – Simple past tense doesn't work here; it doesn't show the regret or the sequence of past events clearly
- D. have done – Present perfect tense; it suggests something up to now, not a specific earlier moment you're regretting

Why A is correct:
This sentence needs the past conditional structure to express an imaginary situation. "If I had time" (not real now) + "I would go" (imaginary result) = the correct grammar for unreal conditions.

Why others are wrong:
- B (will have): Creates future conditional ("If I will have time..."), which is grammatically incorrect—we don't use "will" in the if-clause of conditionals.
- C (have): Present tense suggests a real, possible situation ("If I have time, I go"), not the imaginary meaning intended here.
- D (has): Wrong subject; "has" goes with "he/she/it," not "I."

A. is ✓

This is a conditional sentence (if-clause + main clause). In English, the if-clause uses simple present tense ("is"), while the main clause uses future tense ("will have"). This is the standard pattern: *If + present tense, then + will + verb*.

Why the others are wrong:
- B. will be – Using "will" in the if-clause is incorrect; only the result clause gets "will"
- C. has been – Present perfect doesn't fit conditional statements about future events
- D. was – Past tense doesn't work for a future condition; we're talking about what *might happen*, not what already happened

Correct answer: A. had attended

This sentence uses the third conditional, which describes an imaginary past situation and its result. The structure is "If + had + past participle, would have + past participle." Since she *didn't* attend the concert (but we're imagining she did), we need "had attended."

Why the others are wrong:

• B. will attend – This is future tense, but the sentence already shows past (would have enjoyed), so it doesn't match.
• C. attends – This is present tense and doesn't fit the "if only" imaginary situation about the past.
• D. has attended – This is present perfect, not the past perfect we need for third conditional.

A. were is correct because this is a hypothetical (imaginary) situation. When talking about unreal conditions, use "if + were" even with singular subjects like "I."

Why the others are wrong:
- B. will be — This suggests a real future plan, not a hypothetical scenario
- C. am — Present tense doesn't work for hypothetical situations
- D. was — This is incorrect grammar for conditional statements; "were" is the proper subjunctive form for all subjects in hypothetical "if" clauses

A. had left ✓

This sentence uses a past conditional (also called third conditional) to imagine a different past outcome. The structure requires "had + past participle" in the if-clause to show what *didn't* happen but would have changed the result.

Why the others are wrong:

• B. will leave – Future tense doesn't fit; we're talking about the past, not future possibilities
• C. leave – Present tense is incorrect; the sentence needs past tense to match the imagined scenario
• D. have left – Present perfect doesn't work here; we need "had left" (past perfect) for this conditional structure

Why A is correct:
"Had" is the correct past tense form for an unreal conditional (wish) sentence. When you wish for something that isn't true now, you use past tense: "I wish I had more time" = I don't have enough time now, but I want to.

Why the others are wrong:
- B (will have): Future tense doesn't work with "wish." You can't wish about the future this way.
- C (have): Present tense is incorrect; wishes describe situations that aren't currently true, requiring past tense.
- D (has): This is third person ("he/she has"), but the subject "I" needs first person form.

A. had caught ✓

This sentence describes a past hypothetical (something that didn't actually happen). It needs the past perfect tense "had caught" in the if-clause to show the action would have occurred before the result (arriving on time).

Why the others are wrong:
- B. catch – Present tense; doesn't fit a past situation
- C. caught – Simple past; doesn't express the hypothetical "what if" meaning needed here
- D. have caught – Present perfect; wrong tense for a past conditional statement