How he solved the puzzle astounded everyone. The underlined part is an example of -

• How he solved the puzzle astounded everyone.
- The underlined part is an example of -Noun clause.

• প্রশ্ন প্রদত্ত বাক্যে, প্রদত্ত বাক্যে 'How he solved the puzzle' clause টি subject হিসেবে বসাতে এটি Noun clause.

• A noun clause is a group of words that band together and act like a noun.
- Noun clauses are used when a single word isn't enough. They're always dependent clauses.

একটি বাক্যের বিভিন্ন স্থানে Noun clause বসতে পারে -
1. subject হিসাবে
যেমন: What you did is known to all.

2. transitive verb এর object হিসেবে
যেমন: I know what you have done.

3. Linking verb এরপরে complement হিসাবে
যেমন: The reason is why they are angry.

4. Preposition এরপরে
যেমন: I am sure of who you are.