"in" translations
inside = “in”
location reference = pointing 
non-inside source = eliminate “in”
​          (ex: in time, major in, expert in, invest in)
come in = enter

examples
(space neutral) "in" vs (location reference) "pointing"
The food is in the kitchen. 

non-inside source 
I was born in 2000.
​
enter (get in, come in)
They got in the house.