Arif works hard.
What part of speech is the underlined word?

সঠিক উত্তর খ) Adverb.
- Arif works hard. Here, the underlined part is - Adverb.
- "Hard" এখানে "works" verb-কে modify করছে।
- এটি বলছে "কিভাবে" সে কাজ করে।
- এটি adverb of manner.

• যে Word কোন Verb, Adjective বা অন্য কোন Adverb কে modify করে তাকে Adverb বলে।
- Adverb of manner:
- যে adverb কোন কিছু কিভাবে হয়/হচ্ছে তা উল্লেখ করে তাকে Adverb of manner বলে।

• Hard: [adverb]
- English meaning: with great effort; with difficulty.

Example:
- Work hard and play hard, that's my motto.
- I'm not surprised he failed his exam - he didn't exactly try very hard!

Source: Cambridge Dictionary.