Laravel：如何在四个或更多表之间链接急切加载？

This is my current relationships

这是我目前的关系

I -> belongsTo -> S //in model I
S -> belongsTo -> C //in model S
C -> belongsTo -> T //in model C

T -> hasMany -> C //in model T
C -> hasMany -> S //in model C
S -> hasMany -> I //in model S
I