Which of the following word is 'verb'?

Which one is irregular verb ? She copied the word - এ বাক্যে copied শব্দটি- 'The door opened automatically'. The verb is this sentence is- Walking in the morning is good for health. Here 'walking' is a/an- 'Huffing and puffing, we arrived at the classroom door with only seven seconds to spare.' In this sentence the verb 'arrived' is- Suddenly finding himself alone, he became frightened. 'Numbering' শব্দটির verb হচ্ছে - The door opened automatically. The verb in the sentence is- I will not let you go.' In this sentence 'go' is a/an- I will not let you go. - in this sentence 'go' is a/an