suǒ yǐ
therefore
as a result
so
the reason why
wàng hū suǒ yǐ
to get carried away
to forget oneself
bù zhī qí suǒ yǐ rán
not recognized for what it is
bù zhī suǒ yǐ
to not know the reason
to not know what to do
wàng qí suǒ yǐ
see 忘乎所以[wang4 hu1 suo3 yi3]
zhī qí rán ér bù zhī qí suǒ yǐ rán
to know that it is so but not why it is so (idiom)