PEP英语三年级下册第三单元儿歌One Two Three Four Five

PEP英语三年级下册第三单元儿歌One Two Three Four Five
One,two,three,four,five.
Once I caught a fish alive.
Six,seven,eight,nine,ten.
Then I let it go again.
Why did you let it go?
'Cause it bit my finger so.(请问so在这里什么意思,怎么翻译?)
Which finger did it bite?
This little finger on the right.