Options:

ক) Because: সে-কারণে; কেননা; যেহেতু।
খ) Unless: যদি না।
গ) Although: যদিও; যদ্যপি।
ঘ) If: যদি।

 অপশন বিবেচনা করে দেখা যায়, শূন্যস্থানে "Although" বসালে বাক্যটি পরিপূর্ণ হবে।

Complete sentence: Although glass is, for all practical, a solid, its molecular structure is that of a liquid.

Source: Accessible Dictionary.

সঠিক উত্তর — ক) Put the book back on the shelf.

• এখানে back verb (put)-কে modify করছে, অর্থাৎ "আগের জায়গায়" বা "ফিরিয়ে" দেওয়া বোঝাচ্ছে।
 এটি adverb।

Options:
খ) He was lying on his back on the sofa.
→ back এখানে noun (পিঠ)।

গ) We were sitting in the back row.
→ back এখানে adjective (row-এর অবস্থান বোঝাচ্ছে)।

ঘ) We drove along miles of twisty back roads.
→ back এখানে adjective (roads-এর ধরন বোঝাচ্ছে)।

Back: [adverb]

• English meaning: to or into the place, condition, situation or activity where somebody/something was before.

• Bangla meaning: আগের অবস্থান, অবস্থা বা কাজে ফিরে যাওয়া।

Example:

• When is he coming back to work?

• He'll be back on Monday.

• Don't forget to bring it back when you've finished with it.

Back: [noun]

• English meaning: the part of the human body that is on the opposite side to the chest, between the neck and the tops of the legs; the part of an animal’s body that corresponds to this.

• Bangla meaning: (মানবদেহ সম্বন্ধে) পিঠ; পৃষ্ঠদেশ; মেরুদণ্ড।

Example:

• He was lying on his back on the sofa.

Back: [adjective]

• English meaning: located behind or at the back of something.

Example:

• We were sitting in the back row.

• We drove along miles of twisty back roads (= away from the main roads).

Source: Oxford Dictionary.

“O Captain! My Captain!”

• রচনা: Walt Whitman।

• উদ্দেশ্য: আমেরিকান প্রেসিডেন্ট Abraham Lincoln-এর মৃত্যুতে লেখা elegy।

• কাঠামো: তিন স্তবকের কবিতা।

• প্রকাশ: ১৮৬৫ সালে।

Walt Whitman (1819–1892)

• American poet, journalist, essayist।

• বিখ্যাত রচনা: Leaves of Grass (1855, landmark in American literature)।

Famous Works

• Leaves of Grass

• O Captain! My Captain!

• Drum-Taps

• Songs of Myself

• A Passage To India