If her brother … here, he would call the police.

Step 1: Analyze the question The sentence is: "If her brother ____ here, he would call the police." The main clause uses "would call", which signals a hypothetical, unreal situation. The brother is not here, so we need the correct verb form for an "if" clause of this type.

Step 2: The concept: the Second Conditional The second conditional talks about unreal or imaginary situations in the present or future.

Structure: If + past simple (or "were"), subject + would + base verb

Examples:

• If I were rich, I would buy a car.
• If she studied harder, she would pass.

In the subjunctive (unreal) mood, "were" is used for all subjects, including he, she, it, I.

Step 3: Test each option

• A. have been: This is a present perfect form and does not agree with the singular subject "her brother". It does not fit a second conditional.
• B. will be: "Will" doesn't belong in an "if" clause, and it clashes with "would" in the main clause.
• C. am: This is first person singular and doesn't agree with "her brother". It is also not a past or subjunctive form.
• D. were: This is the subjunctive past form used for unreal conditions, and it matches "would call".

Step 4: Answer Correct sentence: If her brother were here, he would call the police.

Exam tip: When you see "would" in the main clause, look for "were" or a past tense verb in the "if" clause. Remember: If + were, … would. Never put "will" or "would" right after "if" in this kind of sentence.