The counter 2本 is used for counting: 2 bottles/pencils (long/thin objects) (Category: 本 (hon) - Long/thin objects, JLPT N5). 二 (ni) + 本 (hon) is regular. No sound changes are triggered.
Context Example
ペンを2本持っています。
Pen o nihon motte imasu.
I have two pens.
Which counter represents "2 bottles/pencils (long/thin objects)"?
Correct! 🎉
You've mastered this conjugation rule. Save this card to your study queue to review and lock it in forever.