“根由”造句

他熬费苦心地描绘了这次野餐的根由.
Laboriously did he describe the genesis of the picnic.

大概这就是我和沙子结下不解之缘的根由.
That's probably why I have an affinity with sand.

这样,他力气的根由人还是不知道.
So his strength was not known.