Out of the given alternatives given choose the most appropriate option.
I _______ smoke when I was 20 years old.

Correct option is B

The correct option to fill in the blank is (b) used to.
• Explanation:
– The phrase “used to” is used to talk about past habits or states that no longer exist.
– The speaker is referring to the past habit of smoking.
• Grammatical rule used:
– Use "used to + base verb" to indicate an activity that was routine or true in the past but no longer occurs.
• Explanation in Hindi:
– "Used to" का प्रयोग किसी ऐसे कार्य या आदत को दर्शाने के लिए किया जाता है जो पहले होती थी पर अब नहीं होती।
• Example:
– I used to play cricket every weekend. ✅
Meanings of the other options:
• (a) use to ❌
– English: Incorrect tense/form without "d".
– Hindi: गलत रूप
• (c) wouldn't ❌
– English: Negative of “would” – suggests refusal, not past habit.
– Hindi: नहीं करता था
• (d) couldn't ❌
– English: Indicates inability – doesn’t match habitual context.
– Hindi: नहीं कर सका