Choose the grammatically correct sentence:

The correct answer is Option (3) → After six months of lessons, my little brother is able to swim across the society pool without stopping.

“Can” or “is able to”:

• “Is able to” shows ability, just like “can”.
• “Is able to” is followed by the base form of the verb. So is able to swim is correct.

Why the Other Options are Incorrect?

Option 1: After six months of lessons, my little brother can able to swim across the society pool without stopping. — Incorrect. “Can” and “able to” mean the same thing, so only one of them is used.

Option 2: After six months of lessons, my little brother is able swim across the society pool without stopping. — Incorrect. “Able” must be followed by “to” before the verb.

Option 4: After six months of lessons, my little brother is able to swimming across the society pool without stopping. — Incorrect. After “able to”, the verb takes its base form, not the -ing form.