Select the most appropriate option to substitute the highlighted segment in the given sentence. If there is no need to substitute it, select ‘No improvement’. Come quickly if you will catch the train.

Correct — D. The trigger is will after if. When an if-clause points to the future, English normally puts it in the present tense and keeps will for the main clause, so 'if you will catch' is faulty.

The sentence means 'if catching the train is what you want'. If you want to says that, and want to gives catch the to-infinitive it needs: 'Come quickly if you want to catch the train' → option (d).

Why the others are wrong

• (a)
  No improvement — Keeps will after if as a plain future. After if, the present tense carries the future; will after if is kept for willingness, as in 'If you will wait here, I'll fetch him'.
• (b)
  If you will have — If you will have catch is not a verb phrase: have needs a past participle (have caught) or to (have to catch). It also keeps the future will after if.
• (c)
  If you have — Without to, 'if you have catch the train' leaves catch as a bare verb straight after have, which is ungrammatical here. The option supplies no to for catch.

A first conditional links a possible future event to its result: 'If he runs, he will get there in time.' The if-clause takes the present simple though it refers to the future, and will goes in the main clause.

An imperative main clause works the same way: 'Come quickly if you want to catch the train', 'Call me if you need help.'

Will can follow if when it means willingness ('If you will wait here, I'll fetch him'), but not as a plain future.

Key facts

• In a first conditional, the if-clause takes the present tense: 'If he runs, he will get there in time.'
• Will belongs in the main clause of a first conditional, not in the if-clause.
• Want takes a to-infinitive: want to catch, not want catch.
• Will after if is possible when it means willingness: 'If you will wait here, I'll fetch him.'

Common traps

• Keeping will after if because the train is in the future — after if, the present tense carries the future
• Picking 'If you have' because 'if you have to catch' sounds right — the option has no to, so catch is left stranded after have

No directly related past PYQ was found.