Which of the following sentences uses a modal verb to express a polite request?

• সঠিক উত্তর হচ্ছে - Could you please open the window?"

• অন্যদিকে,
• You must call your supervisor.
- uses 'must' modal verb to indicate prayer.

• May Allah bless you.
- uses 'may' modal verb to indicate certainty and obligation.

• They might go to the concert.
- uses 'might' modal verb to indicate possibility.

• Modal auxiliary verb:
- এটি বিভিন্ন অর্থ বহন করে।
- সাধারণত potential ও uncertain কোনোকিছুতে নির্দেশ করতে ব্যবহৃত হয়।
- Model 'auxiliary verb' হলেও do, does কিংবা did কোনো model verb নয়।
- এর পর সাধারণত verb এর present form ব্যবহৃত হয়।
- Modal auxiliary verb এর পর to ব্যবহৃত হয় না।

• Model auxiliary verb: can, could, will, would, shall, should, may, might, and must.
- কয়েকটি Modal Auxiliary Verb এবং তাদের General Function হলো:
- Will (asking),
- Would (requesting),
- Shall (asking),
- Should (suggestion),
- Can (ability),
- Could (requesting + ability),
- May (possibility + permission + prayer),
- Might (possibility + suggestion),
- Must (certainty + obligation),
- Dare (bold assertion),
- Ought to (moral obligation + suggestion),
- Used to (habit), etc.

Source: Applied English Grammar & Composition by P. C. Das.