Question:
“The fact that plants produce oxygen through photosynthesis is crucial for life on Earth.”

• Here, ‘that plants produce oxygen through photosynthesis’ is an example of a Noun Clause.

Explanation (Modified):

1. Noun Clause: একটি subordinate clause যা noun-এর কাজ করে, যেমন subject, object, complement বা noun/pronoun-এর apposition।

2. এখানে ‘that plants produce oxygen through photosynthesis’ একটি Noun in apposition, কারণ এটি ‘fact’ সম্পর্কে অতিরিক্ত তথ্য দিচ্ছে।

3. Apposition: noun/pronoun সম্পর্কিত অতিরিক্ত তথ্য যা তাকে modify করে না। তাই এটি adjective clause নয়।

4. Usage of Noun Clause:

   • Subject হিসেবে

   • Object হিসেবে

   • Complement হিসেবে

   • Preposition-এর object হিসেবে

   • Noun/pronoun-এর apposition হিসেবে

Clause vs Phrase:

• Clause: একটি finite verb বা সমাপিকা ক্রিয়া থাকে।

• Phrase: finite verb ছাড়া থাকতে পারে এবং tense অনুযায়ী structure থাকে না।

সুতরাং, ‘that plants produce oxygen through photosynthesis’ একটি Noun Clause।

Sentence:
Since he didn't understand the question, he asked for clarification.

• Adverbial Clause of Reason: Since he didn't understand the question

Explanation:

• Explains why the action happens.

• Usually begins with because, since, as.

Examples:

• Since I lost my phone, I couldn’t call you.

• Since we finished our work, we went out.

Quick Tip:

• Adverbial Clause = subordinate clause that works like an adverb (time, place, reason, purpose, condition, manner, degree, result, concession).