Correct

所以然

/ suǒ yǐ rán /
Strokes
https://i.cchatty2.com/filters:format(webp)/fit-in/684x0/img/202102/所以然-Chinese-idioms-Cchatty-27e9401a-48d2-4a81-8c29-a5a6ba4d8bd9-1612777109.jpg

Collocation

1
知其然而不知其所以然
2
说出所以然
3
不明白所以然

Definition

所以然

Literally means:

so and then

Actually means:

the whys and the where-fores

It refers to the reasons or wherefores of things.

指事情形成的原因或道理。

Example

Used as object. (作宾语)
1
Yǒuxiē
有些
rén
zhī
liǎojiě
了解
shìqing
事情
shì
zhèyàng
这样
de
  
,
ér
lexiè
了解
shìqing
事情
suǒ
xíngchéng
形成
de
yuányīn
原因
  
,
zhè
jiàozuò
叫做
zhī
rán
ér
zhī
不知
suǒrán
所以然
  

Some people only know that things are like this, and don't understand why things are formed, which is called "knowing it but not knowing why."

2
duì
tuánhuǒ
团伙
de
nèiqíng
内情
bìng
zhīdào
知道
  
,
shěnwèn
审问
le
bàntiān
半天
  
,
wèn
chū
suǒrán
所以然
lái
  

He didn't know about the gang, and I interrogated for half a day, and I couldn't find one.

3
yàoshi
要是
kàn
wán
zhèxiē
这些
wén
文字
hái
míngbái
明白
suǒrán
所以然
de
huà
  
,
jiù
zài
kàn
xià
zhèxiē
这些
piàn
图片
  
,
wén
文字
piàn
图片
一起
kàn
yīnggāi
应该
gēng
róng
容易
jiě
理解
le
  

If you read these words still do not understand so, then look at these pictures, text and pictures together should be easier to understand.