I am surprised at his behaving so rudely. Here 'behaving' is

• I am surprised at his behaving so rudely. Here 'behaving' is a- Gerund.
- In this sentence, "behaving" is a gerund, and "his" is the possessive adjective preceding it.

• Gerund:
- Verb এর সাথে ing যোগ হয়ে যদি noun এর কাজ করে অর্থাৎ Verb ও noun এর কাজ করে, তাহলে তাকে Gerund বলে।
- সংক্ষেপে: Gerund = Verb + ing = noun = Verb + noun.
- It is a word ending in "-ing" that is made from a verb and used like a noun:
- Gerunds don’t describe action—they act as nouns.

• Possessive adjective এর পর gerund বসে৷
- preposition এবং gerund (verb + ing) এর মাঝে Possessive Adjective বসে।
- structure: preposition + Possessive Adjective + gerund (verb + ing).
- যেমন- প্রশ্ন প্রদত্ত বাক্যে his হলো possessive adjective; তাই এরপর gerund হিসাবে 'behaving' বসেছে।